True Hamsters (Cricetinae) of the Palaearctic Region Authors Boris Kryštufek Georgy Isidorovich Shenbrot January 2025 Title True Hamsters (Cricetinae) of the Palaearctic Region Authors Boris Kryštufek (Slovenian Museum of Natural History, Vertebrate Department, and Science and Research Centre Koper, Mediterranean Institute for Environmental Studies) Georgi Isidorovich Schenbrot (Ben-Gurion University of the Negev, Jacob Blaustein Institutes for Desert Research, Mitrani Department of Desert Ecology) Review Ivan Horáček (Charles University, Faculty of Science) Jan Decher (Leibniz-Institute for the Analysis of Biodiversity Change, Museum Koenig Bonn) Language editing Henrik Ciglič Technical editors Jan Perša (University of Maribor, University Press) Marina Bajić (University of Maribor, University Press) Graphics material Sources are own unless otherwise noted. 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CIP - Kataložni zapis o publikaciji Univerzitetna knjižnica Maribor 599.323.51(035)(1-021.21)(0.034.2) KRYŠTUFEK, Boris, 1954- True hamsters (Cricetinae) of the palaearctic region [Elektronski vir] / authors Boris Kryštufek, Georgy Isidorovich Shenbrot. - 1st ed. - E-knjiga. - Maribor : University of Maribor, University Press, 2025 Način dostopa (URL): https://press.um.si/index.php/ump/catalog/book/932 ISBN 978-961-286-940-3 (PDF) doi: 10.18690/um.fnm.1.2025 COBISS.SI-ID 221238019 ISBN 978-961-286-940-3 (pdf) 978-961-286-941-0 (hardback) DOI https://doi.org/10.18690/um.fnm.1.2025 Price Free copy For publisher Prof. Dr. Zdravko Kačič, Rector of University of Maribor Attribution Kryštufek, B., Shenbrot, G. I., (2025). True Hamsters (Cricetinae) of the Palaearctic Region. University of Maribor, University Press. doi: 10.18690/um.fnm.1.2025 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Table of Contents Preface ........................................................................................................................................... 1 Acknowledgements ....................................................................................................................... 1 Taxonomy and nomenclature ....................................................................................................... 3 Taxonomic history .................................................................................................................................................. 3 Family-group names ............................................................................................................................................... 5 Genera and species ................................................................................................................................................. 7 Geographical settings .................................................................................................................... 9 Characteristics of true hamsters ................................................................................................... 11 External appearance ............................................................................................................................................. 11 Skin derivatives...................................................................................................................................................... 11 Soft-body anatomy ............................................................................................................................................... 15 Penis and os genitale ............................................................................................................................................ 17 Skull ........................................................................................................................................................................ 18 Dentition ................................................................................................................................................................ 21 SUBFAMILY: CRICETINAE FISCHER, 1817 – TRUE HAMSTERS .................................. 26 Key to tribes and genera ................................................................................................................. 27 TRIBE: Cricetini Fischer, 1817 ................................................................................................... 29 SUBTRIBE: Cricetina Fischer, 1817 ........................................................................................... 29 GENUS: Tscherskia Ognev. 1914 – Rat-like Hamsters ................................................................................... 30 Tscherskia triton (Winton, 1899) – Common Rat-like Hamster ....................................................................... 31 Subspecies group triton ......................................................................................................................................... 38 Tscherskia triton triton (Winton, 1899) .................................................................................................................. 38 Tscherskia triton incana (Thomas, 1908) .............................................................................................................. 38 Subspecies group nestor ......................................................................................................................................... 38 Tscherskia triton nestor (Thomas, 1907) ............................................................................................................... 38 Tscherskia collina (G. Allen, 1925) – Tsinling Rat-like Hamster ....................................................................... 39 GENUS: Cricetulus A. Milne Edwards, 1867 – Lesser Hamsters ................................................................... 41 SUBGENUS: Cricetulus A. Milne Edwards, 1867 ............................................................................................ 43 Cricetulus barabensis (Pallas, 1773) – Striped Lesser Hamster ........................................................................... 44 Subspecies group barabensis .................................................................................................................................. 52 Cricetulus barabensis barabensis (Pallas, 1773) ........................................................................................................ 52 Cricetulus barabensis fumatus Thomas, 1909 .......................................................................................................... 53 Cricetulus barabensis ferrugineus Argyropulo, 1941 ................................................................................................ 53 Subspecies groups griseus ...................................................................................................................................... 54 Cricetulus barabensis griseus A. Milne Edwards, 1867 ......................................................................................... 54 Cricetulus barabensis pseudogriseus Ishakova, 1974 ................................................................................................. 55 Cricetulus sokolovi Orlov & Malygin, 1988 – Sokolov’s Lesser Hamster ........................................................ 56 SUBGENUS: Ourocricetulus New Subgenus ...................................................................................................... 59 Cricetulus longicaudatus (A. Milne Edwards, 1871) – Long-tailed Lesser Hamster ......................................... 59 ii TABLE OF CONTENTS. Cricetulus longicaudatus longicaudatus (A. Milne Edwards, 1871) ........................................................................ 63 Cricetulus longicaudatus dichrootis Satunin, 1903 .................................................................................................... 64 GENUS: Nothocricetulus Lebedev, Bannikova, Neumann, Ushakova, Ivanova & Surov, 2018 – Grey Hamsters ................................................................................................................................................................ 64 Nothocricetulus migratorius (Pallas, 1773) – Grey Hamster ................................................................................ 64 Nothocricetulus migratorius migratorius (Pallas, 1773) ............................................................................................. 76 Nothocricetulus migratorius phaeus (Pallas, 1779) .................................................................................................... 76 Nothocricetulus migratorius unnamed subspecies .................................................................................................. 77 GENUS: Allocricetulus Argyropulo, 1933 – Eversmann’s Hamsters ................................................................. 77 Allocricetulus eversmanni (Brandt, 1859) – Common Eversmann’s hamster .................................................... 82 Allocricetulus eversmanni eversmanni (Brandt, 1859) ............................................................................................... 86 Allocricetulus eversmanni pseudocurtatus Kartavtseva & Vorontsov, 1992 ................................................................ 87 Allocricetulus curtatus (Allen, 1925) – Mongolian Eversmann’s hamster ......................................................... 87 GENUS: Cricetus Leske, 1779 – Common Hamsters ...................................................................................... 90 Cricetus cricetus (Linnaeus, 1758) – Common Hamster ..................................................................................... 92 SUBTRIBE: Cansumyina – New Subtribe ................................................................................ 105 GENUS: Cansumys G. Allen, 1928 – Gansu Hamsters ................................................................................. 105 Cansumys canus G. Allen, 1928 – Gansu Hamster ........................................................................................... 105 TRIBE: Mesocricetini – New Tribe .......................................................................................... 111 GENUS: Mesocricetus Nehring, 1898 – Golden Hamsters ............................................................................. 112 Species group auratus .......................................................................................................................................... 117 Mesocricetus auratus (Waterhouse, 1839) – Syrian Golden Hamster .............................................................. 117 Mesocricetus raddei (Nehring, 1894) – Radde’s Golden Hamster .................................................................... 121 Mesocricetus raddei raddei (Nehring, 1894) ........................................................................................................... 125 Mesocricetus raddei nigriculus (Nehring, 1898)...................................................................................................... 126 Species group newtoni .......................................................................................................................................... 126 Mesocricetus newtoni (Nehring, 1898) – Romanian Golden Hamster ............................................................. 126 Mesocricetus brandti (Nehring, 1898) – Brandt’s Golden Hamster ................................................................. 130 TRIBE: Urocricetini – New Tribe ............................................................................................. 135 SUBTRIBE: Urocricetina New Rank ......................................................................................................... GENUS: Urocricetus Satunin, 1902 – Tibetan Hamsters ................................................................................ 136 Urocricetus kamensis Satunin, 1902 – Satunin’s Tibetan Hamster ................................................................... 139 Urocricetus lama (Bonhote, 1905) – Ladak Tibetan Hamster.......................................................................... 141 Urocricetus lama lama (Bonhote, 1905) ............................................................................................................... 143 Urocricetus lama alticola Thomas, 1917 ............................................................................................................... 143 SUBTRIBE: Phodopina – New Subtribe .................................................................................. 144 GENUS: Phodopus Miller, 1910 – Desert Hamsters ....................................................................................... 145 Phodopus roborovskii (Satunin, 1902) – Desert Hamster .................................................................................. 145 GENUS: Cricetiscus Thomas, 1917 – Hairy-footed Hamsters ...................................................................... 150 Cricetiscus sungorus Pallas, 1773 – Siberian Hairy-footed Hamster ................................................................ 153 Cricetiscus campbelli (Thomas, 1905) – Mongolian Hairy-footed Hamster ................................................... 155 Cricetiscus campbelli campbelli (Thomas, 1905) .................................................................................................... 157 Cricetiscus campbelli crepidatus (Hollister, 1912) .................................................................................................. 158 References .................................................................................................................................. 159 Index to the technical names ..................................................................................................... 177 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Preface The present volume on true hamsters (subfamily the current DNA-aided phylogenetic reconstructions. Cricetinae) completes the taxonomic review of the We hope that the present work provides novel views family Cricetidae in the Palaearctic biogeographic and will be of interest to experts engaged in medical region. The review was initiated by a volume on voles zoology, epidemiology, biostratigraphy, and lemmings (subfamily Arvicolinae). Although zooarchaeology, population ecology, biodiversity Cricetinae and Arvicolinae are closely related, they conservation, museum collection management and differ profoundly in their morphology, physiology, several other biological subdisciplines. Many of them, ecological role and relations to humans. Contrary to the though working with various true hamsters on daily Holarctic voles and lemmings, the true hamsters are basis, are baffled by the taxonomic changes and endemic to the Palaearctic realm. While Arvicolinae are discordant classifications used in different sources. the most speciose rodent group in temperate and boreal Eurasia (128 species listed in Kryštufek & Shenbrot This review is based on our first-hand experiences with 2022), the true hamsters contain merely 19 species. various species of true hamsters throughout Europe Hamsters are also less abundant in their habitats and and Asia, gained during the last half-century of our not so well represented in mammal collections. professional work. In 27 museums and collections across Europe, Asia and the USA, we examined well The entire group has been thoroughly reviewed in the over 3,000 voucher specimens. Maps were derived from 7th volume of the Handbook of the Mammals of the a basis containing 12,530 locality points. We studied World (Pardiñas et al. 2017), which focused on natural literature on the topic, including original publications history. Our review provides a complete and for nearly every taxonomic name published since 1758; independent list with descriptions, identification keys, the reference list contains over 700 titles. And last, but detailed distributional maps and basic taxonomic details not least, we discussed various issues of taxonomy, allowing the user “to interpret intelligently and zoogeography and biology with experts who actively cautiously the results of taxonomists labour” (Corbet study particular groups. We have received invaluable 1978: 1). In particular, we are attempting to provide for assistance from many experts, and their comments and continuity between the earlier morphology-based suggestions were most helpful, though, as usual, the taxonomies, karyology-based species delimitations and opinions and mistakes remain our own responsibility. TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Acknowledgements This work would not been possible without help of Ambulance, Muta, Slovenia) supplied us with Phodopus curators who granted access to collections and helped sungorus and Mesocricetus auratus; Jenő J. Purger furnished with advice and information. We thank (collection us with C. cricetus and Tilen Begovič with Mesocricetus acronym is parenthesized; for full information see list auratus; while Ivaylo Raykov (Museum of Natural of collections at the end of this chapter): Nataliya History, Varna) and Cătălin Stanciu (Oceanographic Abramson (ZIN), Hermann Ansorge (SMG), †Kurt Research and Marine Environment Protection Society Bauer (NMW), Petr Benda (NMP), Steffen Bock Oceanic-Club, Constanţa, Romania) supplied us with (NHMBe), Gabriel Chişamera (GANHM), Gábor Mesocricetus newtoni from Bulgaria and Romania, Csorba (MNM), Aleksandra Davydova (ZIN), Linda respectively. Gordon (NMNH), Tamás Görföl (MNM), Anneke van Heteren (ZSM), Rainer Hutterer (ZFMK), Paula In summary, we used resource of the following 27 Jenkins (BMNH), †Dieter Kock (SMF), Katrin zoological collections (abc by acronyms): Krohmann (SMF), Vladimir Lebedev (ZMMU), Frieder Mayer (NHMBe), Hendrik Müller (ZCML), Nedko − Natural History Museum (formerly British Nedyalkov (NHMS), Milan Paunović (PMB), Roberto Museum Natural History), London, UK (BMNH); Portela Miguez (BMNH), Alexandr A. Pozdnyakov − Cambridge University Museum of Zoology, (SZM), Irina Ruf (SMF), Nataliya Spasskaya (ZMMU), Cambridge, UK (CUMZ); Friederike Spitzenberger (NMW), Katharina Spreitzer − Field Museum of Natural History, Chicago, USA (MZD), †Gerhard Storch (SMF), Ognyan Sivilov − Grigore Antipa National Museum Natural History, (ZCSU), Vladimir Vohralík (ZCCU), Leonid L. Voyta Bucharest, Romania (GANHM); (NMW), †William Stanley (FMNH), Klara Stefen (FMNH); (ZIN), Frank Zachos (NMW). Mojca Jernejc Kodrič − Museum of Comparative Zoology, Harvard (PMS) provided invaluable help with vouchers in the University, Cambridge, USA (MCZ); Slovenian Museum of Natural History. − Hungarian Natural History Museum, Budapest, In addition to our own examination of museum Hungary (MNM); vouchers in the collections listed above, we received − Museum of Zoology, Dresden, Germany (MZD); photographs of the following taxa: type and paratype of Cansumys canus − National Museum of Natural History, Ukrainian in MCZ by Mark Omura; Tscherskia triton and the type of Academy of Sciences, Kyiv, Ukraine (NHMAS); Cricetulus sokolovi in ZMMU by Vladimir Lebedev; − Cricetus cricetus and Mesocricetus in NHMS, Naturhistoriches Museum Basel, Switzerland NHMAS, TSUK, and MCZ by Nedko Nedyalkov; (NHMBa); Mesocricetus in GANHM by Gabriel Chişamera; Cansumy − Natural History Museum Berlin, Germany canus in FMNH by Rainer Hutterer; a partly melanistic (NHMBe); C. cricetus from northern Serbia by Jenő J. Purger − National Museum of Natural History, Sofia, (Department of Animal Ecology, University of Pécs, Bulgaria (NHMS); Hungary); and Cricetulus barabensis in PMBg by Milan − Smithsonian National Museum of Natural History, PMS. We furthermore thank those who provided − National Museum, Prague, Czech Republic (NMP); frozen and alcoholic specimens which allowed us to − Paunović. David Kunc photographed various taxa in Washington D.C., USA (NMNH); Natural History Museum, Vienna, Austria (NMW); study soft-body parts: Zlatko Golob (Veterinarian − Natural History Museum, Belgrade, Serbia (PMB); 2 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. − Slovenian Museum of Natural History, Ljubljana, reproduction in this volume: Gabriel Chişamera Slovenia (PMS); (Bucharest, Romania), Magomed Magomerasulovich − Chunkov, Wolfgang Hock (Neudietendorf, Germany), Senckenberg Research Institute and Natural History Museum, Frankfurt a/M, Germany (SMF); Christian Kern (Berlin, Germany), Irina V. Kartavtseva − (Vladivostok, Russia), Alenka Kryštufek (Ljubljana, Senckenberg Museum of Natural History Görlitz, − Kabanov (Moscow), Konstantin A. Rogovin (Moscow), Siberian Zoological Museum, Institute for Klaus Rudloff (Berlin, Germany), Georgy Ryurikov Systematic Zoology and Ecology of Animals, Germany (SMG); Slovenia), Nedko Nedyalkov (Sofia, Bulgaria), M. − Russian Academy of Sciences, Siberian Branch, (Georgia), Annegret Stubbe (Halle-Wittenberg, Germany), Alexei V. Surov (Moscow, Russia), Yu. Novosibirsk, Russian Federation (SZM); Yarovemko (Dagestan), Frank Zachos (Vienna, Zoological Museum, Taras Shevchenko National Austria). University of Kyiv, Ukraine (TSUK); − Zoological Collection, Charles University, Prague, Science and Research Centre Koper, Slovenia, granted Czech Republic (ZCCU); permission to reproduce Figures 2, 16, 20, 25 and 26 − Zoological Collection, Martin Luther University, from Kryštufek & Vohralík (2009). Halle-Wittenberg, Germany (ZCML); − Zoological Collection, Sofia University “St. For help with literature, we thank: Gabriel Chişamera Kliment Ohridski”, Sofia, Bulgaria (ZCSU); and Viorel Gavril (Institute of Biology, Bucharest, − Zoological Research Institute and Museum Romania), Magomed Magomerasulovich Chunkov, Alexander Koenig, Bonn, Germany (ZFMK); Peter Čerče (Science and Research Centre, Koper, − Zoological Institute and Zoological Museum, Slovenia), Alenka Jamnik (PMS), Vladimir Lebedev Russian Academy of Science, St. Petersburg, (ZMMU), Ahmad Mahmoudi (Urmia University, Russian Federation (ZIN); Urmia, Iran), Katharina Spreitzer and Alexander Bibl − (NMW), Alexandr Pozdnyakov (SZM), and Alexei V. Zoological Museum of Moscow State University, Moscow, Russian Federation (ZMMU); Surov. Helena Motoh (Science and Research Centre − Koper) provided help with Chinese texts. Zoological State Collection, Munich, Germany (ZSM). We express our gratitude to Franc Janžekovič We were fortunate to benefit from specialists who (University of Maribor, Slovenia) for his interest on our generously shared their knowledge and provided project and continuous support. We extend additional information: Vladimir Lebedev (ZMMU), Ji gratefulness to the University of Maribor, University ř i Mlikovsky (Prague, Czech Republic), Alexei V. Surov Press for publishing this book and to Jan Perša for his and Nataliya Yu. Feoktisova (A. N. Severtsov Institute careful editorial work. of Ecology and Evolution, Moscow, Russia), and Magomed Magomerasulovich Chunkov and Kamil’ This research received support from the SYNTHESYS Zubairovich Omarov (Caspian Institute of Biological Project http://www.synthesys.info/ (to B.K.) which Resources, Dagestan Federal Research Institute RAS, was financed by the European Community Research Makhachkala, Russia). Infrastructure Action under the FP7 Integrating Activities Programme. Further funding was provided We further thank photographers for providing photos by the Slovenian Research Agency through research of living hamsters and generously allowing their core funding No. P1-0255 (B.K.). TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Taxonomy and nomenclature The overall frame for our taxonomic underlying is Linnaean hierarchy provided no taxonomic level explained in our earlier work on the Palaearctic voles between the genus and order. The concept of family is and lemmings Arvicolinae (Kryštufek & Shenbrot attributed to Fischer (1817) who established a family 2022) and is thus not repeated here. group name Cricetinorum for true hamsters. Fischer’s name was ranked either as a family (Cricetidae; Gray Taxonomic history 1825) or a subfamily (Cricetinae; Murray 1866, Winge 1887). Alternatively, Cricetus was classified as member Common hamster of Muridae (Illiger 1811, Gray 1821, Gervais 1854, Cricetus cricetus was validly named in the 12th 1859, Blasius 1857, Fitzinger 1867, Alston 1876) or edition of Systema Naturae (Linnaeus 1758), unsurprisingly as a member of the genus rarely Aspalacidae (Gray, 1825). As the content of Mus . Shortly afterwards, Pallas (1773, 1779) named further 8 species, hamsters was loosely defined, these animals were still classifying them as members of frequently classified along with various Nearctic Mus ; these names represent 3 currently valid species ( (Lesson 1827, 1842) and Neotropical rodents (Winge Cricetulus barabensis, Nothocrocetulus migratorius, Cricetiscus sungorus 1887, Thomas 1888, Flower & Lyddeker 1891), ). Erxleben (1777) transferred taxa named by Linnaeus and Pallas including chinchillas Chinchilla (Geoffroy 1803, Lesson into genus 1827), jirds and gerbils (Gerbillinae) (Kaup 1835), and Glis , but obviously did not see them as a coherent entity against other members of this genus; Malagasy Nesomyinae (Major 1897, Winge 1887, e. g. Trouessart 1897, Miller & Gidley 1918). The hamster he used a vernacular name ‘hamster’ (in German; ‘khomyak’ in Russian) only for family continued to contain a number of genera, tribes Cricetus . At about the same time, Leske (1779) introduced and subfamilies which are now classified into distinct Cricetus as a generic name for the common hamster and two squirrels, families, i. e. Calomyscidae, Muridae, Spalacidae, and European souslik Nesomyidae (cf. Simpson 1945). Around Simpson’s Spermophilus citellus and Alpine marmot time, Cricetinae thus contained between 57 (Ellerman Marmota marmota ; he was not aware of hamsters named by Pallas. 1941) and 66 genera (Vorontzov 1959a). The prevailing opinion was that “…the present group [Cricetidae] is The first to merge all hamsters, and only hamsters, the most difficult group of all living Rodents to arrange under the same generic name ( in any natural order” (Ellerman 1941: 327–328), while Cricetus ) was Johann Friedrich Gmelin (1792); he defined them as “having Rinker (1954: 9) pointed on “… the confusion and pouches in the cheeks, and short hairy tails” (p. 506). disagreement which exist in regard to the Gmelin (1792) classified interrelationships of the cricetine genera”. Cricetus into subdivision coined a new name ‘Buccati’ (“les rats à pochettes dans Central questions which puzzled taxonomists into the th Cunicularii of a division Mures. In 1805, however, he la bouche”; Gmelin 1805: 327) which was occasionally late 20 century were interrelationships between true in use (as Mures buccati) for the rest of the century hamsters and the Nearctic hamster-like rodents on the (Brants 1827, Tullberg 1899). Alternatively, hamsters one hand, and the mouse-like hamsters Calomyscus on were diagnosed by their complete clavicle (“rongeurs the other hand. Calomyscus was included into Cricetinae claviculés”; Milne Edwards 1834: 353; Desmarest 1820, as a closest relative to true hamsters (Argyropulo 1933b, Cuvier 1817) or by a curved mandibular corpus and the c, Ellerman 1941, Simpson 1945, Ellerman & angular process raised above the line of symphysis Morrison-Scott 1951, Corbet 1978, Gromov & (Waterhouse 1839b). A reader should keep in mind that Baranova 1981, Pavlinov & Rossolimo 1987), but is 4 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. now in a family Calomyscidae as its sole extant genus. 2. Sectio B – Criceti myoidei seu leucosterni [mouse-like Particularly problematic for a sound taxonomic setting hamsters with white chests]; diagnosed by usually were convergences of true hamsters towards the white (rarely rusty) chest, convex braincase and large American taxa, both externally (e. g. between Cricetus and interparietal bone (wider than long); Chinchillula; Herskovitz 1962) and dentally (Thomas 2.1. Divisio I – dorsum without longitudinal stripe; 1888). Towards the end of the 19th century, the Old- content: Nothocricetulus migratorius (accedula, arenarius World hamsters (Cricetus sensu lato) and the New-World and phaeus were ranked as distinct species) and “Hesperomys with number of subgenera” (Thomas 1888: Allocricetulus eversmanni; 133) were merged into a single genus Cricetus (Flower & 2.2. Divisio II – dorsum with a distinct longitudinal Lyddeker 1891, Thomas 1888). Contrary to this, stripe; content: Cricetulus barabensis (as furunculus) and Ellerman (1941) stressed that no cricetid genera were Cricetiscus sungorus. common to both hemispheres; see also Vorontzov (1959a, b). Trouessart (1904) split Cricetus with 14 extant species, into 4 subgenera: Karyological data which started emerging in the early Cricetus with the current Cricetus cricetus (as 3 species: 1950s retrieved profound differences between true cricetus, nigricans and fuscatus), Nothocricetulus migratorius hamsters and American cricetids (Makino 1951, (as accedula), Allocricetulus eversmanni, and Cricetulus Matthey 1952, 1960, 1961); this line of evidence was barabensis (as furunculus); supplemented by detailed morphological study (Vorontzov 1959a). Further supportive evidence was Mesocricetus with the current M. raddei (nigriculus as a full provided by nucleotide sequences (Conroy & Cook species), M. brandti (koenigi as a species in its own 1999, Steppan & Schenk 2017). True hamsters right), M. auratus, and M. newtoni; (Cricetinae) are currently classified as one of 5 subfamilies of the family Cricetidae. The remaining Cricetulus with the current Nothocricetulus migratorius (as 4 subfamilies are the Holarctic Arvicolinae and the New distinct species: phaeus, atticus, kozlovi, and arenarius), World Neotominae, Tylomyinae, and Sigmodontinae Phodopus roborovskii, Cricetiscus sungorus, Cricetulus (Pardiñas et al. 2017). Cricetidae form, along with longicaudatus (as dichrootis), and Cricetulus barabensis (as Muridae (a sister family to Cricetidae), Nesomyidae and 2 distinct species: obscurus and griseus); Calomyscidae, the clade Eumuroida within the superfamily Muroidea; Eumuroida have no formal Urocricetus with the current Urocricetus kamensis, Cricetulus taxonomic standing. longicaudatus, and Tscherskia triton. The interrelationships of hamster genera posed a By the 1930s, all major representatives of true hamsters similarly complex issue. Although Cricetulus was named were already known and in 1933 a capital revision by A. already in 1860s (Milne-Edwards 1867), subsequent I. Argyropulo followed; it was published first in Russian authors continued to classify all true hamsters as Cricetus (Argyropulo 1933b) and in the same year also in (Alston 1876, Winge 1887, Tikhomirov & Korchagin German (Argyropulo 1933c). Argyropulo recognized 3 1889, Anderson 1891, Trouessart 1904). A need for genera: (1) Cricetus (with Mesocricetus as a subgenus), (2) taxonomic revision of hamsters was, however, apparent Phodopus, and (3) Cricetulus (with Allocricetulus and in the mid-19th century (Giebel 1855), with Brandt Tscherskia as subgenera). Ellerman (1941) and Ellerman (1859) splitting Cricetus into 2 sections on the basis of & Morrison-Scott (1951) followed this classification, colouration; 1 of these sections was further split into 2 however, they elevated Mesocricetus to a genus in its own “divisions”: right. Vorontsov (1957) did the same with Allocricetulus and Tscherskia, although he was not consistent in this. 1. Sectio A – Criceti genuini seu melanosterni [true hamsters These steps brought the number of recognized genera with black chests], diagnosed by black ventral fur to 6. and cranial traits (skull depressed, interparietal bone triangular and small); content: C. cricetus; Taxonomy and nomenclature 5. Figure 1: Phylogenetic reconstructions showing relationships among genera of Cricetinae based on different markers. I – The most parsimonious tree from cladistic analysis of 55 character-states of bulla tympany. Calomyscus clustered as a basal branch in the Urocricetus + Cricetiscus + Phodopus lineage (not shown). Modified after Potapova (2005). II – The most parsimonious tree from cladistics analysis of chromosomal characters. 1 – Cricetulus barabensis; 2 – C. longicaudatus, 3 – C. sokolovi. Modified after Romanenko et al. (2007). III – Cladogram based on data for 62 phenetic characters and 145 character-states. 1 – Cricetulus longicaudatus; 2 – C. barabensis, C. sokolovi. Modified after Ross (1992: 59a). IV – Molecular phylogeny as inferred from a concatenated alignment of 5 nuclear and 1 mitochondrial genes. Modified after Lebedev et al. (2018a). In the late 1950s, Vorontsov initiated a series of studies number of species and genera to the current one. The devoted to various aspects of hamster morphology most noteworthy achievement of the last decade was a (Vorontsov & Gurtovoi 1959, Vorontsov 1957, 1958, transfer of the migratory hamster into a genus in its own 1960, 1962, 1969, Vorontzov 1959a). This resulted in a right (Nothocricetulus) (Lebedev et al. 2018a). comprehensive revision of “primitive hamsters” of the Old- and New World (Vorontsov 1982) and Family-group names st furthermore enabled the 1 cladistic analysis, which was conducted by Ross (1992). Ross examined all living true True hamsters are currently classified as a subfamily hamsters and restored Cansumys and Urocricetus as valid Cricetinae. In earlier times, when Cricetinae still genera. Her analysis revealed for the first time close encompassed various myomorphous rodents that are phylogenetic relationships between Urocricetus and now in different subfamilies of Cricetidae Phodopus. On the other hand, Ross (1992) failed to (Neotominae, Tylomyinae, and Sigmodontinae), in recognize the isolated position of Mesocricetus. This was Spalacidae (Myospalacinae), Calomyscidae, and accomplished in molecular phylogenies (Neumann et al. Nesomyidae, true hamsters were ranked as a tribe 2006, Lebedev et al. 2018a) that steadily brought the Cricetini. So far, there was no attempt, however, to 6 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. arrange hamster genera into more than 1 family-group 3.1. Subtribe Urocricetina (Urocricetus; 2 ranked either as tribe or subfamily. species) 3.2. Subtribe Phodopina new subtribe At least 4 comprehensive assessments of phylogenetic (Phodopus, Cricetiscus; 3 species) relationships among hamsters have been published over the last 3 decades. These assessments were based on different markers (Figure 1): morphological (Potapova 2005), chromosomal (Romanenko et al. 2007), morphological and chromosomal (Ross 1992), and molecular (Neumann et al. 2006, Lebedev et al. 2018a). Romanenko et al. (2007) and Lebedev et al. (2018a) came to the same conclusion regarding the major hamster lineages. Since divergences between these lineages (> 7.5 Mya) largely predate heterogeneity at generic level (< 8.3 Mya; Figure 2), we classify them as tribes and subtribes. 1. Tribe Cricetini 1.1. Subtribe Cansumyina new subtribe 1.2. Figure 2: Histograms of pairwise divergences (in million years; Subtribe Cricetina ( Tscherskia, Cricetulus, Mya) at 4 taxonomic levels of true hamsters: tribal, generic, specific Nothocricetulus, Allocricetulus, Cricetus (Cansumys; 1 species) ; 9 and infraspecific levels. Values given for each level are: mean species) ±standard deviation; minimum–maximum; (number of pairwise 2. Tribe Mesocricetini new tribe (Mesocricetus; 4 comparisons). Based on data in Neumann et al. (2006), Meshchersky species) & Feoktisova (2009), Lebedev et al. (2018a, b), and Gureeva (2022). 3. Tribe Urocricetini new tribe Figure 3: Cumulative curve for species of true hamsters (Cricetinae) as function of time. Blue circles show new species-group names, red circles show valid species as currently recognized; arrows point to the additions of valid species: A – Linnaeus (1758); B – Pallas (1773); C – Waterhouse (1839a); D – Brandt (1859); E – A. Milne-Edwards (1867); F – Nehring (1894); G – Nehring (1898a, b, 1899a); H – Satunin (1902, 1903), Thomas (1905); I – G. M. Allen (1925); J – G. M. Allen (1928); K – Orlov & Malygin (1988). Spade suits at the top indicate recognitions of new genera: 1 – Cricetus Leske, 1779; 2 – Cricetulus A. Milne-Edwards, 1867; 3 – Mesocricetus Nehring, 1898c; 4 – Urocricetus Satunin, 1902; 5 – Phodopus Miller, 1910: 6 – Cricetiscus Thomas, 1905; 7 – Tscherskia Ognev, 1914; 8 – Cansumys G. M. Allen 1928; 9 – Allocricetulus Argyropulo, 1933b; 10 – Nothocricetulus Lebedev et al. 2018a. Taxonomy and nomenclature 7. Genera and species a general agreement that the number of subspecies was the highest in Nothocricetulus migratorius, i. e. 13–16 The majority of currently recognized genera (7 genera subspecies, depending on the author. On the other out of total 10) were named between 1898 and 1933 hand, opinions differed radically in C. cricetus, with 9 and , i. e. 11 subspecies in Argyropulo (1933c) and Ellerman in a period of 35 years (Figure 3). Genera are small, containing between 1 species ( (1941), respectively, but with only 3 subspecies in Cansumys, Nothocricetulus, Phodopus Ellerman & Morrison-Scott (1951). ) and 4 species ( Mesocricetus ); mean = 1.9 species / genus. Genera diverged between 2.35 Mya ( Table 1: Taxonomic revisions of true hamsters (Cricetinae), Allocricetulus–Cricetus ) and 8.32 Mya ( Tscherskia and the remaining Cricetina; Jiang et al. 2024). published since 1900 with the number of species recognized by an author (authors) and the number of currently valid species. The bulk of currently valid species (8 species out of # recognized # valid Year Authors species species total 19) were named between 1894 and 1905, i. e. in a 1904 Trouessart 24 15 period of 11 years (Figure 3). At about same time, the 1933b,c Argyropulo 15 14 1941 Ellerman 15 14 concept of polytypic species and subspecies replaced 1951 Ellerman & Morrison-Scott 11 10 the earlier idea of immutable species and varieties. The 1978 Corbet 14 14 shift, however, was possible thanks to methodological 1980 Corbet & Hill 14 14 1982 Honacki et al. 19 16 innovations, above all collecting small mammals by 1986 Corbet & Hill 18 15 small, cheap and easily portable traps, and preparing the 1992 Ross 20 18 1993 Musser & Carleton 18 18 animals as standard “museum specimens” (Hutterer & 1995 Pavlinov et al. 18 18 Kryštufek 2020). This accelerated further naming, and 1998 Panteleyev 19 17 49 new species group names for true hamsters were 2003 Pavlinov 18 18 2005 Musser & Carleton 18 18 proposed in the 1900–1940 period, i. e. ½ of all names 2006 Pavlinov 18 18 published since Linnaeus (1758). 2017 Pardiñas et al. 18 18 2020 Burgin et al. 18 18 From the current perspective, the species diversity of In this review, we addressed subspecific taxonomy. true hamsters was fully comprehended by the 1990s, Eight species are recognized as polytypic with 2–5 when settled at 18 species (Musser & Carleton 1993, subspecies (median = 2 subspecies per polytypic Pavlinov et al. 1995) (Table 1); a single species is a very species). Three species are classified as monotypic and recent addition (Jiang et al. 2024). Species of true further 3 species are admittedly polytypic. Any hamsters diverged 1.02–3.88 Mya (mean = 1.697 Mya; application of trinomials would, however, be premature Figure 2). The bulk of speciation events happened at this stage. during the Early Pleistocene. We provide full references for all species-group names, Subspecies taxonomy suffers from all the weaknesses together with type localities. If quoted from the original that burden this issue in the Palaearctic mammalogy. source, the type locality is in quotation marks and any The majority of infraspecific divergences date back c. 1 additional information is in square brackets. Type My, therefore suggesting that subspeciation was an localities for all available names are shown on the event of the Middle and Late Pleistocene. Infraspecific species maps. Main compilations for the genus- and diversity at the level of traditional trinomial taxonomy species-group names are Trouessart (1897, 1904, 1910), is, however, poorly documented and only 3 taxonomic Palmer (1904), Miller (1912), Allen (1940), Ellerman reviews addressed subspecies of all true hamsters. (1941), Ellerman & Morrison-Scott (1951), Corbet These reviews were published between 1933–1951 and (1978), Pavlinov & Rossolimo (1987), Kretzoi & are more compilations of subspecific names rather than Kretzoi (2000), and Musser & Carleton (2005). genuine taxonomic revisions. In any case, c. 10 species were classified as polytypic, with up to c. 15 subspecies per species. Median number of subspecies per polytypic species was 3–4.5, depending on the source . There was 8 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. guFi re 4: Species density o rue hf t am ster ith rrow 6s p sp ecoint t ies . ion lue a w reg s. B ions witho reg sp 5 ec ; red aies rrow p oin ts t o a TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Geographical settings True hamsters are exclusively Palaearctic group and are Distributional ranges of 19 species of true hamsters found at present only in temperate parts of Europe and cover surface areas between 24,000–7.1 million km2, i. Asia. Hamsters however occupied also the Palaearctic e. a difference of approximately 300-fold. Frequency Africa in various periods of Neogene and Quaternary distribution is skewed towards small areas (mean = (McKenna & Bell 1997). Their ranges stretch from the 1,075,896 km2, median = 494,197 km2), with half of all Rhine Valley in the west reaching Sea of Japan and ranges measuring 92,870–1,401,000 km2. Yellow Sea in the east. The northern border is largely defined by the southern extension of boreal forests Along the elevational gradient, hamsters range from (Laptev 1958) and overlaps pretty closely with large below sea level (–26 m in the Caspian Depression) to rivers, the Volga–Kama system in the west and the 5,114 m, hence elevational ranges are between 354– Amur River in the Far East; in-between, the northern 4,729 m (Figure 5). The mean (= 2,487 m) and median range encompasses the upper reaches of Irtysh, Ob, (= 2,423 m) are remarkably similar, and ½ of species Yenissei, and Lena. In the south, hamsters rarely cross have ranges between 1,703–3,243 m. Only 3 species the 30th parallel; minor transgressions are in southern (Cricetus cricetus, Mesocricetus auratus, M. newtoni) occupy Iran, southern Pakistan, and Nepal (Figure 4). The low elevations (< 1,000 m a. s. l.), and 2 species, both overall range closely matches the zone of Palaearctic from the genus Urocricetus, are tied to high elevations (> steppes and semideserts. Although the range overlaps 2,000 m) (Figure 5). also large sections of the deciduous forest zone, hamsters are absent from close-canopy forests; the only exception is Cansumy canus. Figure 5: Elevational ranges for each of true hamsters. 10 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Up to 6 species of hamsters are locally sympatric (China). Patches having 4–6 species of hamsters are (Figure 4), however, a great majority of their range is highly fragmented and scattered to the east of line occupied by 1–2 species. Areas with 3 species are Tobol–Balkhash Lake. Thus, assemblages with 5 scattered, though still reasonably compact in the (1) species are present in (1) the Great Lake Depression, steppes to the north of the Caucasus (Ciscaucasia); (2) (2) the Khangai Mts., in (3) western Gobi in Mongolia, east-central basin of the River Volga; (3) the watershed (4) central and southern Khingan Range (eastern Nei of Tobol, Irtysh and upper Ob in northern Kazakhstan Mongol) and in (6) the Lang Shan Mts. at the north- and adjacent Russia; (4) western and central Mongolia; west corner of the Ordos Loop. The Lang Shan is the (5) east-central Nei Mongol, Hebei, Shanxi, and top hot-spot in species richness with 6 hamster species northern Henan; (6) Ningxia, Gansu and Shaanxi (Figure 4). TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Characteristics of true hamsters True hamsters are myomorphous rodents, and hardly protruding off the hairs in Mesocricetus, characterized by (1) well developed internal pouches, Phodopus, Cricetiscus, and Allocricetulus; in adult short-(2) a mid-ventral sebaceous gland in the umbilical tailed males, the tail is further obscured by distended region, (3) rooted, tubercular and brachyodont molars scrotal sacks. The tail is longest (> ½ of length of head with cusps arranged in two longitudinal rows, (4) a pair and body) in Urocricetus kamensis, Tscherskia and of anteroconids / anteroconulids in 1st molars, (5) a Cansumys. Eyes are on average larger and ears are longer high and falcate coronoid process, (6) a reduced fibula than in voles. Limbs are short and powerful; feet are fused with the tibia on its distal end, (7) a two essentially as in arvicolines, but shorter and broader chambered stomach consisting of a corneous with not much size difference between the fore and forestomach and glandular stomach, and (8) a primitive hind paws. They have 5 digits each but the front thumb pattern of cephalic arterial supply system with stapedial is always distinctly smaller and usually reduced to a mere artery preserved in its entirety (Argyropulo 1933b, c, vestige (Figures 33, 80, 101 & 109). Palms and soles are Ellerman 1941, Vorontsov 1960, 1982, Bugge 1970, densely hairy in Phodopina and seasonally also in some 1985, Wahlert 1984, Ross 1992, Chernova et al. 2022a. other hamsters (e. g. Cricetulus sokolovi). b). Skin derivatives External appearance True hamsters are of generalized external form without The rhinarium (Figure 7), a specialised skin surrounding extreme specializations. They range in appearance from the external openings of the nostrils (external nares), is slender (Figure 6a) to stout and roundish (Figure 6b) of general murine type and does not differ appreciably and vary in size from small ( Phodopus has body mass of from that seen in Arvicolinae. It is situated on the tip of 10.5–19 g) to moderately large (body mass in Cricetus is the snout at a distance from the upper incisors which is up to 860 g). At least some hamsters are sexually approximately equal to the height of rhinarium. dimorphic in size with either males (Tscherskia triton, Rhinarium is hairless in all hamsters except Phodopini, Cricetiscus, C. cricetus) or females (Mesocricetus auratus) in which the dorsum, the infranarial portion and the alae being the larger sex. The tail is shorter than ½ length of nasi are hairy. head and body in great majority of species. It is vestigial Figure 6: Extreme hamster forms, the slender form (a – Nothocricetulus migratorius) and the stout roundish type (b – Mesocricetus). Art Jan Hošek. Used with permission of the Science and Research Centre Koper. 12 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. deeply into the dermal layer and also contains large hair follicles, thus obscuring the boundary between the 2 layers, which is a distinctive feature of Cricetinae (Chernova et al. 2022a). All hamsters are densely furred. Hairs cluster into distinct bundles; there are c. 80–100 such bundles per cm2 in C. cricetus (Chernova et al. 2022b). The fur is usually soft, rarely silky (Urocricetus, Phodopus) or slightly rough (Tsherskia). Pelage is denser on the back than below; in C. cricetus, there are 2,100–2,140 hairs per cm2 on the back, ~ 1,750 hairs per cm2 on the flanks and Figure 7: Rhinarium of common hamster Cricetus cricetus from ~1,255 hairs per cm2 on the belly. The pelage, however, Baranja, north-eastern Croatia. Abbreviation p. is for portion. is more homogeneous than in other muroids (Chernova Photo: B. Kryštufek et al. 2022a); members of Phodopina even lack guard The auricle is moderately large to large, rounded or hairs (Feoktisova 2008). Differentiation into tires and different categories of hair is loose, though the elongated and usually protruding above the fur. overhairs tend to be thicker. In C. cricetus their diameter Structurally it is like in Arvicolinae (Kryštufek & ≈ 85 – 93 μ m compared to ≈ 40–63 μ m in guard hairs; Shenbrot 2022: 12), though it tends to be hairier in downy hairs are the thinnest (≈ 10 –55 μ m). Besides, the hamsters (Figure 8). The antitragus is frequently of same hair type tends to be thicker on the back than weak prominence. below. The cross-section of hair shaft is either oval or cylindrical and the thick medulla presumably increases the insulation capacity of the pelage (Chernova et al. 2022a, b). At withers, hairs of C. cricetus measure from 8–15 mm (guard hairs) to 21–26 mm (overhairs) in length and are longer dorsally than ventrally (Chernova et al. 2022b). In hamsters of small or medium size (Cricetulus, Allocricetulus, Nothocricetulus), dorsal hairs usually measure 8–13 mm. Hairs are of similar structure in Cricetinae as in Muridae and Arvicolinae. The scale- Figure 8: like pattern of the cuticle follows the wave-type (Trapp Left auricle in Cricetiscus sungorus (left), Mesocricetus auratus (middle), and 1979), which is characteristic also of Arvicolinae. Allocricetulus eversmanni (right). Photo: B. Kryštufek Digits are equipped with curved and laterally The juvenile and seasonal moults in Cricetina (Cricetulus, compressed claws which closely resemble those in Allocricetulus, Nothocricetulus and Tscherskia) follow the arvicolines. The front claws are frequently longer and sublateral type, which is characteristic also of more curved; the thumb has a small claw or a flat nail. Arvicolinae. In this type, the new hair starts growing There are typically 5 palmar and 6 plantar pads (Figures from the underside of the flanks and proceeds both 33, 80 & 101). In Phodopina, where this number is towards the dorsum and the belly. Cricetiscus has a reduced to 3 pads ( Cricetiscus), or a single one (Phodopus), unique moulting pattern in which the hair is firstly the vestiges of pads are concealed under dense hairs replaced in several patches along the spine and moult (Figure 109). progresses across the rest of the back, towards the head, the flanks and the belly (Kryltzov 1964). The integument is thin, with weakly developed epidermis and dermis layers. Unique for the subfamily Hamsters have on average a richer colouration than is a well pronounced subcutaneous tissue with hair other species of Cricetidae and Muridae. Cricetus, and to follicles. The adipose subcutaneous tissue penetrates a lesser degree also Mesocricetus and Cricetiscus, have Characteristics of true hamsters 13. blotches of bright and dull fur. Such bright colouration were present at frequencies <0.01%; unsurprisingly, associates with aggressive defending behaviour and is they were detected thanks to huge number of skins presumably aposematic (Vorontsov 1982); analogy with (104–106 skins) gathered in pelt trade (Gershenson the Norwegian lemming (Lemmus l. lemmus; Kryštufek & 1945, Kayser & Stubbe 2000, Kryštufek et al. 2016). Shenbrot 2022) is obvious. Some hamsters, however, Melanistic variant is not known in Allocricetulus, have a prominent black spinal (mid-dorsal) stripe along Cricetulus s. lat, and Urocricetina (Vorontsov 1982). the back (Cricetulus barabensis and Cricetiscus). Thirteen colour variants are known in captive-bred Furthermore, there are blackish blocks on crown and Syrian golden hamsters Mesocricetus auratus (Robinson head, shoulders, and flanks in Cricetiscus and Mesocricetus. 1968). Contrasting light (white) patches are common on the side of the head (Cricetiscus, Cansumys) or behind the auricle (Mesocricetus). Golden hamsters (Mesocricetus) and Allocricetulus eversmanni have a dark sternal stripe across the throat and chests; black underside is a norm for Cricetus and is frequently present also in Mesocricetus raddei. The area of extended cheek pouches shows a contrasting pattern in Mesocricetus (Figure 14a) and Allocricetulus (Figure 59) with a prominent oblique post- auricular stripe. Leaving aside extreme colour variants (e. g. melanistic or albino hamsters), the pelage is frequently monochromatic, either brown or grey dorsally; the belly is lighter, usually white. Demarcation line along the flanks is frequently distinct, either straight or sinuous; if the latter, the line is bowed upward over Figure 9: Dorsal colour pattern of anterior body in (a) C. cricetus, (b) the shoulders, hips, and sides. Hamsters occupying Mesocricetus brandti , and (c) M. newtoni . Colour features: 1 – rostral Nothocricetulus rocky habitats ( , Urocricetus ) are of similar light patch; 2 – cheek light patch; 3 – sub-auricular light patch; 4 – colour to rock-dwelling mountain voles postauricular light patch; 5 – light-edged ears; 6 –subauricular Alticola ; the similarity is close enough to cause occasional (shoulder) stripe; 7 – collar stripe; 8 – neck (collar) patch; 9 – misclassifications of museum vouchers (Argyropulo postero-lateral extension of a sternal patch; 10 – axillary light patch; 11 – crown patch; 11 – occipital stripe. Photo: B. Kryštufek 1936: 118 footnote; Lim & Ross 1992). Cricetiscus sungorus shows seasonal polyphenism with white winter On the head are long, slender, coarse, tapered, and pelage (Figures 111a2 & 119a). As is common in the keratinised tactile hairs, the whiskers ( vibrissae) which are majority of other muroids, including Arvicolinae, the classified according to their position, arrangement and basal 2/3–4/5 of a hair is slate. White ventral hairs usually function. Syrian golden hamster has on each side of the have the basal ½ slate; occasionally, ventral hairs are head 35 straight and stiff mystacial whiskers (vibrissae white to base. mystaciales), 2 supraorbital whiskers (v. supraorbitales) and 1 gental whisker (vibrissa gentale); the mystacial vibrissae In the opinion of Vorontsov (1982), black colour appear in 7 longitudinal rows. At least some hamsters variant is present at various frequencies in what he (e. g. C. cricetus, Nothocricetulus migratorius) also have called “tricolour hamsters”, i. e. Cricetus and Mesocricetus antebrachial whiskers (v. antebrachialis). Labial vibrissae, (brandti and raddei). Some populations of common located posterior to the proper whiskers, are smaller, hamster C. cricetus contain high proportion (up to disorganised and not independently mobile (Wineski >80%) of black individuals, which are usually classified 2009). Cricetus has 30 mystacial vibrissae in 4–5 distinct as melanistic. Black variant is currently still present in rows (Reznik et al. 1979). The length of mystacial populations of C. cricetus, where it was reported in the whiskers grades from the shortest to the longest mid-18th century. Other aberrant colour variants are vibrissae in the antero-posterior direction. Whiskers are rare in wild populations. Approximately 10 variants up to 34–38 mm long in Mesocricetus auratus, M. brandti which were reported in free-living common hamsters and M. newtoni, 32–39 mm in Cricetus cricetus, 32 mm in 14 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Allocricetulus eversmanni, 35 mm in Nothocricetulus discoloration of the fur along the mid-ventral line. migratorius, and 22 mm in Cricetulus barabensis. They are Length × width (in mm) of the gland is 9–15 × 1–2 in 166–191 μm thick in Cricetus (Chernova et al. 2022b). In Nothocricetulus migratorius, and 4.1 × 3.5 in Cricetiscus Mesocricetus, the maximum lateral extent of the mystacial campbelli (Ross 1995), In C. cricetus, the mid-ventral vibrissal field may reach 45.5% of the hamster’s body glandular area is seen as 5 × 5 mm2 area of bare skin length (Wineski 2009). with a central excretory opening and specialized hairs. Cricetulus similarly shows a glandular area with hairs. Hamsters have a pair of large sebaceous glands, The mid-ventral gland can resume a shape of glandular organised as pads and situated on the flanks sac, either with specialized hairs (osmotrichia; e. g. in approximately in the middle between the shoulder and Phodopina) or without them ( Allocricetulus) (Chernova the hip (postero-lateral glands or flank organs; Figure et al. 2022a). Vrtiš (1932) believed for umbilical organ 63). Each gland assumes shape of oblong-oval structure to be synapomorphic to Cricetinae, however, it occurs which protrudes from the surrounding skin due to its also in Peromyscus and related genera (Richmond & intense black colouring and hairs which differ from Roslund 1952). Postero-lateral and mid-ventral glands those of the surrounding skin. The position of flank are of different histological structure. True hamsters organ is indicated by a small non-pigmented area before also have cheek gland situated on the cheeks. sexual maturity and appears at the age of 1–2 weeks in M. auratus (Magalhaes 1968). Glands are present in both sexes but are larger in males; their length in Allocricetulus curtatus is 3.8 mm in males and 2.25 mm in females (Chernova et al. 2022a). In Mesocricetus auratus males, the gland is 8.5 mm long and 6 mm wide; corresponding dimensions in male Cricetus are 20–40 and 10 mm, respectively. Flank glands are covered by thin epidermis and produce secretion for territorial marking (Lipkow 1954). Hamsters vigorously scratch the flank gland with Figure 10: Ventral side of a carded skin of a male grey hamster hind foot, which is immediately followed with a perineal usually referred to as the umbilical glandular organ ( Nothocricetulus migratorius. Arrow points to a mid-ventral gland, glandula drag; besides, the exudate is spread on the substrate by abdominalis). Photo: B. Kryštufek feet as the animal moves about (Skirrow & Ryšan 1976). The postero-lateral glands in Cricetinae and Arvicolinae are homologous (cf. Kryštufek & Shenbrot 2022: 13). True hamsters have unpaired mid-ventral gland (glandula abdominalis) (Figure 10) which was found in all Cricetinae studied so far: Urocricetus, Phodopus, Cricetiscus, Mesocricetus, Tscherskia, Allocricetulus, Cricetus, Cricetulus, and Nothocricetulus (Vrtiš 1932, Lipkow 1954, Vorontsov & Gurtovoi 1959, Reznik et al. 1974, Vorontsov 1982). The gland is larger in males but is frequently reduced or entirely absent in females. Mean length (in mm) of the gland in males / females is 12.2 / 6.7 in Allocricetulus curtatus, 10.7 / 6.5 in A. eversmanni, 7.8 / 4.0 in Cricetulus sokolovi, and 6.33 / 2.75 in C. barabensis griseus (Chernova et al. 2022a). The gland consists of a group of enlarged compound sebaceous glands covered with a very thick epidermis. It occurs in the umbilical region (hence the Figure 11: Complete set of mammary glands (nipples) in hamsters. umbilical glandular organ) as a cutaneous invagination a – Cricetini and Urocricetini; b – Mesocricetini. The number of devoid of hair, frequently in combination with a greasy teats in Mesocricetini varies from 14 to 22 (7–11 pairs); the lowest count of 7 pairs is shown in this figure. Characteristics of true hamsters 15. The majority of hamsters have 4 pairs of nipples developed labial lobes that do not come close together (papillae mammae; 8 nipples in total), which are organized (Figures 7 &12). The hard palate is covered by a mucous in 2 pairs, the pectoral and the inguinal pair, respectively membrane which forms transverse ridges (rugae (Figure 11a). Golden hamsters (Mesocricetus) have 14–22 palatinae). Usually, there are 6–8 ridges; the posterior 3– nipples (Magalhaes 1968, Vorontsov 1982), which are 4 ridges are intermolar ridges (Tullberg 1899, Buchtová evenly spread between the pectoral and the inguinal et al. 2005), and the remainder are the diastemal region (Figure 11b). Nipples are inconspicuous in non- (antemolar) ridges (Figure 12). lactating females, however, their position can be recognized by hair swirls. Each of the teats has a single Main part of the floor of the oral cavity is formed by galactophore, which is typical of the remaining long, narrow and thick tongue (lingua) which was used Myomorpha (Ching-Mei & Anderson 1975). in phylogenetic studies of Cricetinae (Vorontsov 1958, Ross 1992) and is therefore covered in greater detail. Soft-body anatomy The internal anatomy is covered in considerable detail for Cricetus (Tullberg 1899, Reznik et al. 1979), and Mesocricetus (Magalhaes 1968, Kittel 1984). Vorontsov (1982) provides extensive comparisons for the entire subfamily (except Cansumys) and its relatives from the family Cricetidae (except Arvicolinae). Subsequently we briefly address digestive system due to its relevancy for generic classification. Figure 13: Tongue of Mesocricetus auratus (a1) and Cricetus cricetus (b1, b2) in dorsal (a1, b1) and lateral view (b2) to show features of surface anatomy. Abbreviations: p.c. – papilla circumvulatus; p.fi. – papillae filiformes; p.fu. – papillae fungiformes; s.m. – sulcus medianus; s.s. – sulcus semilunaris. Photo: David Kunc (a1) and B. Kryštufek (b) The size of a tongue (length × width; in mm) is 30–55 × 10–12 in Cricetus cricetus, 24 × 7–8 in Tscherskia, 12 × Figure 12: The diastemal palate and molar region in Cricetus cricetus 3.6 in Cricetulus barabensis, 16.5 × 4–4.5 in Nothocricetulus as viewed from below to show features of surface anatomy. migratorius, 15.6 × 6.8 in Allocricetulus eversmanni, 12.8 × Abbreviations: a.l.r. – anterior longitudal (palatal) ridge; I sup – upper 3.7–4.2 in Cricetiscus sungorus , 23–28 × 9.1 in Mesocricetus incisor; l.l. – labial lobe (of the upper lip); M 1 , M 2 , M 3 – 1 st , 2 nd and raddei 3 rd , and 15–18 × 6.2 in M. brandti (Vorontsov 1958, upper molar, respectively; t.d.r. – transverse diastemal ridges; t.i.r. – transverse intermolar ridges. Photo: B. Kryštufek Reznik et al. 1979). The tongue consists of the longer anterior part (oral part; apex linguae) and the shorter base The free margins of the lips form a three-cornered flap (intermolar eminence; corpus linguae) which are divided which seals the mouth opening when closed. The by a semilunar groove (sulcus semilunaris) (Figure 13). incisors are seen from the outside, however, the Dorsal surface of the tongue is covered by papillae entrance to the cavity is closed by comparatively poorly filiformes which are numerous, minute and packed close 16 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. together; usually, they are larger on the base of the and 12–15 mm wide when empty (Reznik et al. 1979); tongue, i. e. posterior to the semilunar groove. These in mature Mesocricetus auratus, distended pouches papillae give the tongue its characteristic rough texture, measure 2.5–5.5 cm in length and ~1 cm in width but contain no phylogenetic information. Ross (1992) (Handler & Shepro 1968; Figure 14a). The pouches are used further 2 types of papillae in her phylogenetic lateral evaginations of the buccal mucosa of the oral analysis of the subfamily. Papillae foliatae are arranged cavity and possess no glands. They consequently have either in 2 rows (Mesocricetini) or in 1 row (the no digestive function but are employed in carrying remaining Cricetinae) at the edge of corpus linguae. food. The pouches extend dorso-caudad over the Papillae fungiformes are found only in the apex. These region of the shoulder. The skin is firmly attached to papillae extend to the tip of tongue (in Cricetulus and underlying muscle only in the ventral thoracic region, Nothocricetulus) or end before the tip (in Cricetus); but is capable of rather extensive movement or frequently, they extend around the apex to the ventral stretching elsewhere (Magalhaes 1968). The posterior surface of the tongue (Allocricetulus, Tscherskia, pulling (retraction) of the pouch is accomplished by Mesocricetini, Urocricetini). All hamsters have a single retractor muscle (musculus trapezius auricularis) which papilla circumvulatus. A crescent-shaped fissure on the originates from the lumbar vertebrae. Its anterior dorsal surface of the tongue on the boundary of the oral portion is 2-headed in hamsters. The antero-dorsal head and basal parts (sulcus semilunaris) is present in reaches the post-auricular region (Tscherskia) or is Allocricetulus, Tscherskia, Cricetus and Mesocricetus, but reduced (remaining Cricetina), while the ventral head absent in the remaining hamsters. Torus linguae is located reaches further anterior and inserts on the lateral or / on the postero-dorsal side of the tongue, behind sulcus and the medial wall of the pouch (Aristov 1988). The semilunaris. Its function is pushing off the soil that extended portions of buccinatorius muscle which entered the mouth during digging by incisors; the torus originates on the rostrum and the mandible and inserts is well developed in Allocricetulus, Tscherskia, Cricetus and short of the caudal end of the pouch aids its emptying Mesocricetus. Median sulcus (sulcus medianus linguae) is a by contraction. The crescentic pouch aperture, which is longitudinal groove on the distal dorsal tongue; in located approximately opposite the posterior 2/3 of the Allocricetulus, the sulcus terminates well before the apex, upper diastema (Figure 14b), is controlled by a but in the remaining hamsters extends to the very tip sphincter (musculus orbicularis oris) which is also part of (Sonntag 1924, Vorontsov 1958, Reznik et al. 1979, the buccinatorius muscle. The inner pouch wall has Ross 1992). thick bands of elastin in the dermis and also consists of folds which become part of the wall when the pouch is All hamsters have paired internal cheek pouches (bursae full. In addition to this, an anteriorly projecting buccales) which are muscular and highly distensible peninsula of highly folded tissue is integrated into the (Figure 14). In C. cricetus, each pouch is 60–70 mm long posteromedial pouch wall, thus allowing for additional Figure 14: Romanian golden hamster (Mesocricetus newtoni) with fully distended cheek pouches (a). Arrows point to extreme ends of the left pouch. Entrance to the right cheek pouch (b) in common hamster Cricetus cricetus. Photo by Gabriel Chişamera (a) and Boris Kryštufek (b) Characteristics of true hamsters 17. increase of the volume when food is stored in the Allocricetulus and Cricetus have 3 ampullae and Tscherskia pouch. The pouches empty into vestibulum oris has 5 of them. They are formed by a colic spiral adjacent retrobuccalis of the oral cavity. When empty, the pouch is to the caecum, while additional ampullae associate with in shape of coarse longitudinal folds which allow for the ascending colon posterior to the colic spiral distension (Keyes & Dale 1944, Priddy & Broddie 1948, (Vorontsov 1962). Intestine is 3.4–3.7-times the length Ryan 1986, Aristov 1988). During feeding, food items of head and body in great majority of hamsters. The are shoved into pouches, transported and hoarded intestine is relatively longer in Urocricetus and inside the burrow (Kryštufek et al. 2020). In C. cricetus, Nothocricetulus (the quotient = 4.0–4.1), Mesocricetus (= pouches filled with air reportedly ensure buoyancy for 5.8–6.9) and Cricetus (= 6.4) (Vorontsov 1962). swimming (Sidorov et al. 2009) and females of M. auratus are said to carry their young inside the pouches (Witte 1971). The stomach consists of two chambers which are sharply separated from each other by the incisurae of the greater and lesser curvatures (Figure 15). These chambers are a blind forestomach or esophageal diverticulum (cardiac part, proventriculus) and a true or glandular stomach (ventriculus glandularis). The two chambers are of approximately the same size. The esophagus enters into the forestomach, and the pyloric region of the glandular stomach empties into the duodenum of the small intestine. Length of the forestomach / true stomach is ~ 18 / 20 mm in Mesocricetus auratus (Magalhaes 1968) and 45–50 / 30–40 mm in Cricetus cricetus (Reznik et al. 1979). The forestomach lacks glands and is lined with simple keratinized (corneous) epithelium; it is putatively the esophageal diverticulum and separated from the mucosal glandular lining of the true stomach by a Figure 15: Stomach cut longitudinally. Schematic drawings in distinct border (margo plicatus). The equal division of Cricetus cricetus (a) and Phodopus roborovskii (b); c – Mesocricetus auratus. keratinized and glandular tissue is characteristic of The keratinized section (forestomach) is shaded grey in (a) and (b). Cricetulus, Tscherskia 1 – from the oesophagus; 2 – to the intestine; fs – forestomach; gs and Mesocricetus . In its more derived – glandular stomach; py – pylorus ; mp – margo plicatus ; gc – greater stage, the corneous epithelium extends into glandular curvature; lc – lesser curvature. (a) and (b) modified from Tullberg section of stomach, but does not cross the isthmus (1899) and Vorontsov (1962), respectively; (c) photo by B. (Cricetus, Allocricetulus). In Urocricetini new tribe, the Kryštufek the isthmus and in All true hamsters, with the exception of Mesocricetus, lack Phodopus occupies the greater part of gall bladder (Ross 1992). keratinized (i.e. non-glandular) section extends beyond glandular stomach (Figure 15b). The margo plicatus is convoluted margo except Allocricetulus. The majority of Penis and os genitale simple, with no added folds in all hamsters with hamsters have glands in the pyloric portion (pyloric glands) which, however, are absent in Phodopus. Callery (1951) introduced the term os genitale to designate either the baculum of the male or os clitoridis The caecum of true hamsters is a large structure and its of the female, and we now follow his nomenclature. retaining capacity exceeds that of the stomach. Its Glans penis and baculum were used in traditional length is up to 150 mm in C. cricetus and 54–82 mm in classification (Argyropulo 1933c) and phylogenetic Mesocricetus auratus. The proximal part usually has at least reconstructions of Cricetinae (Vorontsov 1982, Ross 1 dilated, ampullary swelling (ampulla coli). Mesocricetus, 1992). 18 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. widespread in Cricetidae. Central denticle is usually the longest and rod-shaped. The proximal part of the bony shaft is markedly expanded laterally and grooved ventrally. Distal baculum remains cartilaginous in Phodopina and is only partially osseous in Mesocricetus; in the remaining hamsters, the distal baculum is more or less completely osseous (Figure 17). In Syrian golden hamster Mesocricetus auratus, the baculum does not reach maximum development until late in the animal's reproductive life (Callery 1951). Figure 16: Glans penis in common hamster Cricetus cricetus (a1–c1), and Syrian golden hamster Mesocricetus auratus (a2–c2) in (a) dorsal view (dorsum penis), (b) lateral view, and (c) ventral view. 1 – glans (glans penis); 2 – body (corpus penis); 3 – dorsal vein; 4 – lateral papilla (papilla lateralis); 5 – central papilla (papilla centralis); 6 – ostium urethrae externum. Photo: David Kunc Penis and baculum are of same basic type as in Arvicolinae. Therefore, when not erected, the penis directs cranidad and flexes sharply caudad; erected Figure 17: Outline of baculum in true hamsters: a – Cricetiscus penis turns cranidad. The glans is cylindrically shaped sungorus; b – Phodopus roborovskii; c – Tscherskia triton; d – Cricetulus with a rounded or truncate distal edge (Figure 16). Many barabensis; e – Nothocricetulus migratorius; f – Allocricetulus eversmanni; g microscopically visible spines are found on its surface. – A. curtatus; h – Cricetus cricetus; i – Mesocricetus brandti. Osseous parts At the top are digit-like processes (papillae, bacular are shaded grey; regions which remain cartilaginous or ossify late are mounds). The three papillae surrounding the urethra, white. Proximal is at the base. Modified from Bittera (1918), Argyropulo (1933c), Tokuda (1941), Callery (1951), Didier (1953), the central and 2 lateral, are frequently of sub-equal size Vorontsov (1982), Ross (1992), and Yiğit et al. (2000). and accommodate the tips of the 3 distal denticles of the baculum (trident). These papillae are present in all Baubellum (os clitoridis) is considerably smaller than the hamsters. Some hamsters also have a dorsally situated baculum and of simpler shape. In Syrian golden lingual papilla and / or ventrally situated 1–3 ventral hamster, it is spatulate and attains its maximum length papillae. (~ 1.5 mm) by the age of 50 days (Callery 1951). Baubellum was not used in taxonomy of true hamsters Positioned in the glans penis is a heterotopic bone so far. called the baculum (os penis or os priapi). The baculum is situated near the centre of the glans and extends for Skull most of its length from the erectile tissue (corpora cavernosa penis) to the terminal papillae. It is of a complex The appearance of skull (Figure 18) is murine in quadripartite type (Figure 17), composed of a bony Urocricetini, Tscherskia, Cansumys, Cricetulus, shaft (proximal baculum) and three finger-like Allocricetulus, and Nothocricetulus (Figures 26, 34, 48, 52, processes (digits or denticles) attached to the tip and 103 & 114). Dorsal profile is more or less bowed, the forming a distal baculum (trident). Such baculum is rostrum is usually broad, braincase is longer than wide Characteristics of true hamsters 19. Figure 18: Cricetus skull in dorsal (a) and ventral (b) views (only half of the skull shown); lateral views of skull (c) and mandible (d). Abbreviations: M1, M2, M3 / M1, M2, M3 – 1st, 2nd and 3rd upper / lower molars, respectively. 20 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. (equidimensional, i. e. circular in Phodopus roborovskii), and the nasals posteriorly transgress the level of lacrimal and the occipital region is occasionally shifted bones. Zygomatic arches are either elliptic (Cricetus) or posteriorly, hence the condyles are seen from above. run parallel (Mesocricetus). Brain-case is approximately as Zygomata are rather weak, either expanding evenly or long as wide with the occipital bone strongly projecting displaying straight arches at their middle. Nasals are backward; condyles are clearly seen from above. Adult fairly long; they taper posteriorly and usually reach the skull is heavily ridged. Supratemporal ridges usually run level of lacrimal bones. Interorbital region shows no from the naso-frontal suture backward, reaching a peculiarities except being ridged in Tscherskia and strong lambdoid crest situated along the posterior Cansumys; usually it is of about same width as rostrum. border of a small interparietal which is of triangular, Parietals are of moderate size, therefore leaving crescentic or rectangular shape. The two ridges closely squamosals to cover a considerable portion of dorsal converge on the posterior frontals and diverge gradually neurocraniaum (e. g. Tscherskia); on the other extreme, towards the lambdoid crest. They never merge into a the parietals expand over the entire roof of the true sagittal crest, though the narrowed area between braincase (e. g. Phodopus roborovskii). Interparietal is of the converging ridges is crest-like in very old variable shape, from octagonal to ligulate. Incisive individuals. Incisive foramina are short to moderately foramina are moderately long to long and frequently long. reach anterior margin of M1. Hard palate terminates at posterior edge of M3 or behind; the length of Hamsters are unique among Muroidea in their mesopterygoid fossa is at least twice its width. variability of zygomasseteric specialization (Figures 19 & 20). The latter denotes the development of anterior The skull is robust and heavy in Cricetus (Figure 18) and portion of lateral masseteric muscle and its insertion on Mesocricetus (Figures 85 & 94). Dorsal profile is nearly the masseteric plate and / or rostrum. Typical of flat, though sloping gradually in front of lacrimal region. Muroidea, including the majority of hamsters Rostrum is clearly wider than the interorbital region, (Urocricetus, Cricetiscus, Tscherskia, Cricetulus, and Cricetus), is myomorhmous zygomasseteric structure (Figure 19a) with well-marked external plate of infraorbital canal (masseteric or zygomatic plate), marked zygomatic spine (keel) and deep zygomatic notch; the notch and the keel are seen in dorsal view. The anterior portion of lateral masseter (masseter lateralis anterior) inserts on the masseteric plate, while the medial masseter (masseter medialis anterior) reaches rostrum through the infraorbital foramen; this is markedly wider above than below. In pseudo-sciuromorphous type (Figure 19b), the zygomatic plate is narrowed to an extent which does not prevent the lateral masseter from reaching the rostrum; the medial masseter likewise inserts on the rostrum through the infraorbital canal which typically has nearly oval outer side (Figure 20). Zygomatic keel and notch are both absent and the anterior edge of zygoma transgresses into the rostrum Figure 19: as a smooth curve (Figure 19b). This type is Dorsal (a1, b1) and lateral (a2, b2) view of the rostral and zygomatic regions, illustrating the variation in the zygomasseteric characteristic of Mesocricetus, Phodopus, Cansumys, and structure in Cricetus cricetus (a) and Mesocricetus auratus (b). The bold Allocericetulus. Transitional morphotypes between these line shows the anterior margin of the masseteric plate (a2) and the extremes were reported in Phodopina and Cricetulus. inferior maxillary root of zygoma (b2). Not to scale. For acronyms Nothocricetulus displays either type of zygomasseteric see Figure 20. structure with all transitions in-between (Lebedev & Potapova 2008). Characteristics of true hamsters 21. Figure 20: Frontal side of the left zygomasseteric region in true hamsters to show differences in size and shape of infraorbital foramen. The foramen is most constricted at top left and most expanded at bottom right: a – Cricetus cricetus; b – Mesocricetus brandti; c – Cricetiscus sungorus; d – Nothocricetulus migratorius; e – Allocricetulus curtatus; f – Phodopus roborovskii; g – Cricetulus barabensis; h – Mesocricetus auratus. Not to scale. Acronyms: fr – frontal bone; if – infraorbital foramen; is – upper incisor; izr – inferior maxillary root of zygoma; M1 – 1st upper molar; mp – masseteric plate; mx – maxillary; na – nasal bone; nc – nasolacrimal capsule; pmx – premaxillary; szr – superior maxillary root of zygoma; zn – zygomatic notch; zs – zygomatic spine; Mandible in Cricetinae is, like in Muroidea, with no Cricetus cricetus (Reznik et al. 1979). Mandibular molars specializations. The mandibular symphysis does not emerge at same age as maxillary (Cricetus) or slightly ossify. Corpus is slender and strongly curved. All earlier (Cricetulus). processes are well developed; coronoid process is sickle-shaped and approximates in size and form the Incisors grow from persistent pulps and have the front angular process. The root of lower incisor usually forms surface coated with enamel, thus leaving the dentine a slight bulge (capsular projection) on the outer wall of naked behind. The enamel layer is 60–65 μm thick on ramus (Figure 18d). the upper incisors and 65–75 μm on the lower incisors (Kalthoff 2006). There is not much variation in this Dentition respect among genera and the thickness obviously does not correlate with body size (Figure 21). Unequal wear Similarly to arvicolines, cricetines have 1 incisor and 3 between the anterior and posterior surfaces results in a molars in each jaw, hence the total number of teeth is chisel point on the anterior crown. The procumbence 16. The dentition is monophyodont. Incisors erupt of the upper incisors is opisthodont in Cansumys and within 24 hours after birth and attain occlusion within Phodopus, and orthodont in the remaining genera. 1 day ( Incisors are moderately broad, with smooth front Cricetulus, Mesocricetus ); in Cricetus , the eruption occurs at days 4–5 postpartum. Growth of lower surface, which is normally pigmented from pale-yellow incisors in Brandt's golden hamster to yellow-orange. The upper incisors are more deeply (Mesocricetus brandti ) is on average 1 cm per month (Lyman & O’Brien 1977). coloured than the lower ones and the intensity increases start extragingival eruption at the age 7–8 days (1 more strongly curved and their alveolar sheet st 1 terminates in front of M . The lower incisors are longer molars), 12–14 days (2 In Syrian golden hamster ( with age. Just like in arvicolines, the upper incisors are Mesocricetus auratus ), molars nd rd molars) and 30–35 days (3 molars), and molar rows come into full occlusion at the and less curved; only their distal ⅓ is erupted, while the age of 40–45 days (Keyes & Dale 1944). Molars erupt proximal ⅔ is seated in the alveolus. The lower incisor between days 10 and 35 postpartum in terminates as a weak capsular projection (processus Cricetulus barabensis alveolaris) posterior to M3 on the labial side of (Kobayashi 1984), and days 10 and 33 in 22 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. mandibular ramus. The extragingival upper incisor may (length ≈ width). In the mandibular row, M1 accounts replace itself with a 1-week period, while the lower for 35–40% of length of the entire row and the incisor requires 2.5–3 weeks. posterior molars M2–3 are of about the same length (Wahlert 1984). On a cross-section, the upper incisors are more robust than the lower ones in all hamster genera studied by The occlusion pattern consists of cusps connected by Kalthoff (2006). Length (thickness) × width ranges ridges with folds and valleys (infolds) between them from 1.3 × 0.8 mm (Phodopus) to 1.7 × 1.5 mm (Cricetus); (Figure 22). Tubercles are arranged in two primary corresponding measurements on the lower incisors are longitudinal rows, the inner (lingual) and the outer from 1.1 × 0.75 mm (Nothocricetulus, Phodopus) to 1.4 × (buccal). In all Cricetinae, 4 main cusps are easily 1.3 mm (Mesocricetus). The upper incisor is recognizable in both the upper and the lower molars. comparatively the narrowest in Phodopus (length-to- These cusps are readily homologized with cusps of a width ratio = 1.6) and the broadest in Mesocricetus and modified tribosphenic molar and are usually Cricetus (= 1.1–1.2). The upper incisor is proportionally denominated as proto-, para-, hypo-, and metacone in the narrowest in Nothocricetulus and Phodopus (= 1.8) and the maxillary row; the extension -conid denotes cusps the broadest in Mesocricetus (= 1.25). in the mandibular row (Hooper 1952, Herskovitz 1962, Topachevskiy & Skorik 1992, Ross 1992). Both 1st molars have anteriorly a pair of conules (M1) or conulids (M1). Rudiments of anterobuccal conules / conulids persist as enamel ridges in the remaining posteriorly located molars. M1 has 4 cones of the major tribosphenic pattern posterior to 2 anterocones. The basic pattern of M1 is modified in M2–3 by marked reduction of the buccal anterocone to a mere ridge and a complete loss of lingual anterocone. The M2 has an additional postero-buccal ridge (posteroloph); its metacone tends toward reduction. Hypocone and metacone are evidently smaller than protocone and Figure 21: paracone on M3 Incisor cross sections of (a) Cricetiscus sungorus , (b) and frequently loose characteristic Mesocricetus auratus, (c) Nothocricetulus migratorius, and (d) Cricetus cusp-like appearance. cricetus. Dentine is shaded grey and enamel is shown in black. Upper incisors are on the top row, lower incisors are on the bottom line. Alternation between the lingual and buccal cusps is Anterior is to the top and mesial is to the right. Modified from Kalthoff (2006) more obvious on the mandibular molars and the buccal series is clearly shifted posteriorly. M1 has 6 cusps and Molars remain rooted throughout life (rhizodont), postero-lingual ridge (posterolophid). The anteroconids though the closure of pulps is retarded in Cansumys; they are smaller than on M1 and frequently reduced to a are cuspidate (polybunodont) and low-crowned crescent enamel ridge; in such cases, the conids are (brachyodont) in the great majority of genera. Cansumys loosely separated by a minute anterior groove. M2–3 is the only extant hamster having high-crowned molars retain the buccal anteroconid, which is also reduced to (mesodont or hypsodont, depending on the author). enamel ridge; caudally is postero-lingual ridge Usually, the number of roots is as follows: 4–5 on M1, (cingulum sensu Niethammer 1982). Entoconid tends 3–4 on M2, and 2–3 on M3; each mandibular molar has towards reduction on M3. On maxillary molars, the 2 roots in an antero-posterior alignment. The 1st molar buccal cusps are higher than the lingual ones, and the is the longest tooth in both rows. In the maxillary row, opposite is true for the mandibular row. M1 accounts for 40–45% of the tooth row, while M3, which is usually the shortest, accounts for 25–27% of The cusps are separated by broad sulci and deep tooth row; M3 is frequently nearly equidimensional occlusal fossae, which are emphasized by wear. Fossae Characteristics of true hamsters 23. become apparent as oval enamel islands (internal the outer side of maxillary molars and on the inner side infolds) in all upper molars, but remain lingually open of the lower molars. There are 2 primary folds on each in mandibular molars. Internal infolds (if) are designated molar, i. e. the anterior (pf1) and the posterior fold (pf2). in the antero-posterior direction as if1 and if2. Grooves The occlusial surface on all upper molars is marked by form re-entrant loops, which are present on the inner X-ridge connections between protocone-paracone and and outer sides of all molars. Primary folds (pf) are on hypocone-metacone. Figure 22: Upper left (A) and lower right (B) molars of a generalized hamster (Cricetinae) showing occlusal structure. Lingual is to the left and anterior is at the top. Dentine is shaded dark grey. Terminology follows Herskovitz (1962) and Ross (1992); acronyms for cones are capitalized and for conulids are given in lower-case letters. The main cones/conulids of tribosphenic pattern are highlighted in bold. AB – anterobuccal conule (buccal anterocone); ab – anterobuccal conulid (buccal anteroconulid); AL – anterolingual conule (lingual anterocone); al – anterolingual conulid (lingual anteroconulid); ent – entolophid; HYP –hypocone; hyp – hypoconid; if1 – first internal fold; if2 – second internal fold; mes – mesolophid; MET – metacone; met – metaconid; PAR – paracone; pf1 – first primary fold; pf2 –second primary fold; PL – posteroloph; pl – posterolophid; PRO –protocone; pro – protoconid. 24 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Abbreviations Molars are abbreviated by the upper-case letter “M” with numbers 1–3 indicating their position in the row; superscript / subscript denotes upper (maxillary) / lower (mandibular) molars. E.g. M2 is the 2nd upper molar. For further abbreviations of molar morphology see Figure 18. 2n diploid number of chromosomes NF fundamental number of chromosomal arms NFa fundamental number of autosomal arms mt mitochondrial (genome, DNA) Cytb cytochrome b (gene, sequence) K2P genetic distance calculated using the Kimura 2-parameter model TMRCA the most recent common ancestor sp. / spp species (singular / plural) ssp. / sspp. subspecies (singular / plural) ky / My thousand / million years kya / Mya thousand / million years ago a. s. l. [elevation] above sea level cf (confer or conferatur = compare) used to refer the reader to other material for comparison with the topic being discussed e. g. (exempli gratia) for example i. e. (id est) that is in litt (in litteris) information communicated in writing l. c. loco citato (in the place cited) s. str. sensu stricto (in a narrow sense) s. lat. sensu lato (in a broad sense) v. versus (against) sic Latin adverb (thus, so, in this manner); inserted after a quotation indicates that the quoted matter has been transcribed or translated as found in the source text, including erroneous spelling SD standard deviation CI confidence interval ~ approximately ≈ almost equal to < / > less than / more than ≤ / ≥ less than or equal / more than or equal TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot SUBFAMILY: CRICETINAE FISCHER, 1817 – TRUE HAMSTERS Mures buccati Gmelin, 1792: 242 (with reference to “Systema Naturae”). Criceti Gmelin, 1792: 242. Buccati Gmelin, 1805: 327. Cricetini Fischer, 1817: 372. Not Fischer von Waldheim (e.g. Gromov & Baranova 1981, McKenna & Bell 1997); in 1817, Fisher still did not hold his noble title with the extension ‘von Waldheim’. Cricetinorum Fischer, 1817: 410. Explicitly proposed as a family. Cricetina Gray, 1825: 342. Criceti Pallas 1831: 160. Proposed as a division of Glires. Cricetinae Murray 1866: 356. The first ranking as a subfamily in modern sense. Cricetidae Rochebrune, 1883: 66. The first ranking as a family in modern sense. Cricotini: Schegolev 1925: 19. Ranked as a subfamily; probably incorrect subsequent spelling of Cricetini. Type genus by tautonomy is “Cricetus Cuv[ier]” in Fischer (1817: 410) (= Hamster Lacépède). The context of true hamsters within the classis Mammalia is as follows: Class Mammalia Linnaeus, 1758 Subclass Theria Parker & Haswell, 1897 Infraclass Eutheria Gill, 1872 Magnorder Boreoeutheria Springer & de Jong, 2001 Superorder Euarchantoglires Murphy, Eizirik, O’Brien et al., 2001 Order Rodentia Bowdich, 1821 Suborder Myomorpha Brandt, 1855 Superfamily Muroidea Illiger, 1811 Family Cricetidae Fischer, 1817 Subfamily Cricetinae Fischer, 1817 Cricetinae are in a sister position against voles and Middle Miocene (McKenna & Bell 1997) or Late lemmings Arvicolianae; the two subfamilies diverged Miocene (Topachevsky & Skorik 1992). Cricetinae approximately 17.23 Mya (95% CI = 14.84–19.67 Mya) contain 9 extant and 15 fossil genera (McKenna & Bell (Lebedev et al. 2018a), i. e. in Early Miocene or lower 1997; this volume). Middle Miocene. Fossils have been known since the TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Key to tribes and genera Fore keys to hamster genera see also Ellerman (1941: 114); major molar cusps alternate; internal fields 338) and Pavlinov et al. (1995: 80–81); for a key to present on upper molars (Figure 117); 2n = 28 species see Corbet (1978: 89–93). ………………………..……………..... Cricetiscus 4a) Subauricular dark stripe is present (Figure 9b, c); 1a) Plantar surface is either partly hairy between the soles are largely nude between the metatarsal pads pads (Figure 101) or is furry throughout its surface and on heels (Figure 80); > 10 mammae; (Figure 109); bullae are flattened, bony eustachian subsquamosal foramen is absent and hamular tube is elongated (Figure 99a) process is not separated from squamosal (Figures ……………………………..2 (tribe Urocricetini) 85 & 94); M3 is larger than M2; width-to-length 1b) Plantar surface is nude or furry posterior to pads ratio for 2nd and 3rd molars < 0.75 (Figures 86 & (Figures 33 & 80); bullae are of normal size, bony 95); entepicondylar foramen is absent in the distal eustachian tube is short (Figure end of humerus (Figure 78a); trident of baculum 99b)…………………………………………....4 is largely cartilaginous even in adults (Figure 17i); 2a) Tail length accounts for > 30% of length of head 2n = 38–44 ……….……………..…. Mesocricetus and body; plantar surface is only partly hairy 4b) Subauricular dark stripe is absent; soles are hairy between pads; 6 plantar pads (Figure 101); spheno- posterior to pads (Figure 33); 8 mammae; frontal foramen is present.……………Urocricetus subsquamosal foramen is present and hamular 2b) Tail length accounts for < 20% of length of head process is separated from squamosal (Figure 34); and body; plantar surface is fully hairy and M3 is smaller than M2; width-to-length ratio for 2nd conceals 1–3 plantar pads (Figure 109); spheno- and 3rd molars = 0.80–1.00 (Figure 35); frontal foramen is absent ……………………….. entepicondylar foramen is present in the distal end …………………………..3 (subtribe Phodopina) of humerus (Figure 78b); trident of the baculum 3a) Spinal stripe is absent (Figure 111c); white ventral (at least the central digit) is osseous (Figure 17d– pelage extends to dorsal side of the tail base h); 2n = 20–34 ……………….. 5 (tribe Cricetini) (Figure 113a); 1 plantar pad (Figure 109a); the 5a) Tail accounts for ~ 70% of head and body length anterior edge of the superior maxillary root of and is thickly clad with shaggy hairs which cover zygoma forms right angle at its junction with the annulation; rostrum is parallel-sided; interparietal rostrum; nasals do not reach the level of lacrimals; is broad and strap shaped; pterygoids are shorter incisive foramens of approximately same length as than the maxillary tooth-row; coronoid process is maxillary tooth-row; upper incisors are short and blunt, not extending beyond the level of opisthodont (Figure 114); major molar cusps sigmoid notch; upper incisors are opisthodont; oppose each other and form transverse lophs; maxillary tooth-row slightly shorter than diastema, upper molars without internal fields (Figure 115); surrounded by a bony ridge (Figure 75); molars are 2n = 34 …………………………..….. Phodopus robust and high-crowned (Figure 76b) 3b) Spinal stripe is present (Figure 111a, b); white ……………………………………..… Cansumys ventral pelage does not extend to dorsal side of the 5b) Tail accounts for < 65% of head and body length tail base (Figure 113b); 3 plantar pads (Figure and is sparsely haired, annulation is exposed; 109c); the anterior edge of the superior maxillary rostrum is narrow anteriorly and widest at root of zygoma forms a smooth curve at its nasolacrimal capsule; interparietal is triangular or junction with the rostrum; nasals reach the level of diamond-shaped; pterygoids are longer than the lacrimals; incisive foramens longer than maxillary maxillary tooth-row; upper incisors are orthodont; tooth-row; upper incisors are orthodont (Figure maxillary tooth-row shorter than diastema, 28 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. without surrounding ridge (Figures 26, 34, 52 & 8a) Zygomatic notch and keel not visible in dorsal 67); molars are weaker and low crowned (Figure view; length of incisive foramina equals ~ ½ of 76a) …………………….... 6 (subtribe Cricetina) diastema length (Figure 52); coronal suture usually 6a) Length of maxillary tooth-row ≥ 6.6 mm; belly is W-shaped; coronoid process is long and extends black throughout; 4 contrasting light patches back to the anterior margin of mandibular condyle present along the side (Figure 63); skull is robust …………………………………….. Allocricetulus with heavy temporal ridges; interparietal is 8b) Zygomatic notch and keel usually visible in dorsal triangular and small (Figure 67) view; incisive foramina evidently longer than ½ of ……………………………………….…. Cricetus diastema (Figure 34 & 48); coronal suture smooth; 6b) Length of maxillary tooth-row < 6.6 mm; no coronoid process shorter and does not extend contrasting light patches along the side; skull is less back to the anterior margin of mandibular condyle heavy and temporal ridges are weak or absent; ……………………………..………………… 9 interparietal is not triangular and extends across 9a) Distal baculum is of about same length as proximal the majority of the cranium roof (Figures 26, 34 & stalk (Figure 17d); fronto-temporal angle of 52) ……………………………...….………….7 parietals closely approaches the posterior orbital 7a) Size larger: length of head and body > 135 mm, edge, sutura squamosa cranii is consequently short in condylobasal length of skull > 34 mm, length of dorsal view (Figure 34); metalophule is absent; no maxillary tooth-row > 4.9 mm; tail long, X-pattern of enamel ridges between the proto- accounting for > 40% of head and body length; paracone and hypocone-metacone of M1–2; distal tail frequently white; bullae are larger and mesolophid absent on M3 (Figure 35 & 44) elliptic; interparietal bone is hexagonal (Figure 26); ……………………...………………..... Cricetulus coronal (fronto-parietal) suture is square-edged; 2n 9b) Distal baculum is much shorter than proximal = 28 ……………..………………….. Tscherskia stalk (Figure 17e); fronto-temporal angle of 7b) Size smaller: length of head and body < 150 mm, parietals does not closely approach the posterior condylobasal length of skull < 34 mm, length of orbital edge, sutura squamosa cranii is consequently maxillary tooth-row < 5.1 mm; tail usually shorter, longer in dorsal view (Figure 48); internal fold 2 is accounting for < 42% of head and body; tail is of closed by metalophule, which creates X-pattern of uniform colour; bullae are smaller and circular; enamel ridges between proto-paracone and interparietal bone is lingulate or diamond-shaped hypocone-metacone of M1–2; mesolophid present (Figure 34, 48 & 52); coronal (fronto-parietal) on lingual side of M3 (Figure 49) suture is rounded or W-shaped; 2n = 20–26 ……………………………....….... Nothocricetulus …………..……………………………………. 8 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot TRIBE: Cricetini Fischer, 1817 Diagnosis and Comparisons. A central tribe of true < 0.75 in Mesocricetini (Lozan 1971). (6) Rostrum is hamsters Cricetinae which contains ½ of extant species the widest at nasolacrimal capsule in Cricetini (with the and occupies the great majority of the range of the exception of Cansumys), but is rectangular with parallel subfamily. The tribe is well defined by nucleotide lateral margins in Mesocricetini. (7) Subsquamosal sequences (Neumann et al. 2006, Lebedev et al. 2018a) foramen is present between hamular process and and chromosomal data (Romanenko et al. 2007). squamosal in Cricetini, but absent in Mesocricetini However, not a single morphological trait is (hamular process is not separated from squamosal). (8) synapomorphic for all Cricetini. (1) Papillae Entepicondylar foramen is present in Cricetini and fungiformes are present only on the dorsal side of the absent in Mesocricetini (Figure 78). (9) Number of tongue and do not extend to its ventral surface as in the mammae is low (8 nipples) in Cricetini but high (> 10 remaining Cricetinae (Vorontsov 1958). (2) Plantar nipples) in Mesocricetini (Figure 11). pads are furry posterior to pads in Cricetini (Figure 33) and in Urocricetina (Figure 101), while they are largely Distribution is Palaearctic, from West Europe to nude in Mesocricetini (Figure 80) and densely furry in Korea, and from southern Siberia and Russian Far East Phodopina (Figure 109). (3) Ossification of distal to the Levant Coast, Iran, Afghanistan and Pakistan, baculum is synchronous with the proximal baculum, north-western India, Nepal, and the Three Rivers while it is heavily postponed or entirely absent in the Source Region (Sanjiangyuan) in China. remaining hamsters (Figure 17). (4) Diploid number of chromosomes (2n ≤ 28) and fundamental number of Content. The tribe includes 2 subtribes (Cricetina and autosomal arms (NF ≤ 42) are both low, while these Cansumyina) with 6 extant genera (Cansumys, Tscherskia, parameters have higher values in the remaining Allocricetulus, Cricetus, Nothocricetulus, Cricetulus) and 10 hamsters (2n ≥ 28 and NF ≥ 48). Cricetini differ from species. Urocricetini by having (1) large and round bullae with short eustrachian tube; bullae are flattened and the SUBTRIBE: Cricetina Fischer, 1817 eustachian tube is long in Urocricetini (Figure 99). (2) Lateral line is serpentinous with deep dorsal expansion Subtribe Cricetina is the central group of true hamsters, of light ventral fur in Urocricetini (Figures 102 & 116), comprising all genera of the tribe Cricetini, except while it is less serpentinous or straight in Cricetini. (3) Cansumys. For comparison see under Cansumyina new Corneous epithelium of the stomach is mainly restricted subtribe. to the forestomach in Cricetini, while it may occupy most of glandular region in Urocricetini (Figure 15). Diagnosis and Comparisons are detailed under Cricetini differ from Mesocricetini in a series of traits. Cansumyina new substribe. (1) Subauricular dark stripe is absent in Cricetini (present in Allocricetulus), while it is present in Distribution is as for the tribe. Mesocricetini (Figure 9b, c). (2) Papillae foliatae are arranged in 1 row (2 rows in Mesocricetini; Vorontsov Content. The subtribe includes 5 extant genera 1958). (3) Gallbladder is absent, but present in (Tscherskia, Allocricetulus, Cricetus, Nothocricetulus, Mesocricetini (Carleton & Musser 1984). (4) M3 is Cricetulus) with 9 species. smaller than M2 in Cricetini and larger in Mesocricetini (Gromov et al. 1963, Ross 1992). (5) Width-to-length ratio for the 2nd and 3rd molars (maxillary and mandibular) is 0.80–1.00 in Cricetini, while the ratio is 30 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. GENUS: Tscherskia Ognev, 1914 – 2002, Wu & Fu 2005, Xie & Zhang 2005b, Wu et al. Rat-like Hamsters 2015, Ding et al. 2016a). Asiocricetus is Tscherskia albipes Ognev [= Cricetus triton Winton]. other hamsters and is as such the least advanced Kishida, 1929: 148. Type species is member of the subfamily. Phylogenetic analyses based Asiocricetus bampensis Kishida [= Tscherskia triton nestor on nucleotide sequences (Lebedev et al. 2018a, Jiang et Tscherskia Ognev, 1914: 102. Type species by monotypy generalized muroid body plan to a greater extent than In Miljutin’s (2011) view, Tscherskia is characterised by Tsherskia: Thomas]. al. 2024) and chromosomal data (Romanenko et al. Argyropulo, 1933b: 241. Incorrect 2007) ranked Tscherskia as a sister genus to the subsequent spelling of Tscherskia Ognev. remaining Cricetina. Application of molecular clock on Tscherkia: Fulton, 1968: 3. Incorrect subsequent spelling the concatenation of five nuclear genes yielded of Tscherskia Ognev. divergence time against the remaining Cricetina of 6.36 Tscherskia as a genus for rat-like hamsters from the varied from 4.8±0.2 to 6.7±1.4 Mya, depending on the southernmost part of the Russian Far East on the calibration point; the recent estimate by Jiang et al. Korean border. He suggested its close links to Nearctic (2024) is significantly higher (8.32 Mya). Chromosomal Taxonomy. Ognev (1914) named and described Neumann (2007) obtained similar divergences, which Mya (95% CI = 4.83–8.01 Mya; Lebedev et al. 2018a). wood rats (Neotoma) and climbing rats (Ototylomys). data returned much lower divergence (2.8 Mya) Ognev, however, overlooked that by than 3 taxa of rat- between Tscherskia and Mesocricetus (Kartavtsev et al. like hamsters had already been named by Winton (1899) 1984a, b) i. e. the genera with the least similar karyotypes and Thomas (1907, 1908a) as members of the genus of any Cricetinae. Cricetulus . Satunin (1902) classified triton into Urocricetus , which he established as a subgenus of Cricetulus and also Fossil record of Tscherskia is contested; remnants from incorporated Urocricetus kamensis and Cricetulus Middle Pliocene pretty closely resemble the extant longicaudatus ; Trouessart (1904) promptly grasped this species. The putative ancestor is either Cricetinus varians arrangement. Tate (1947) spread different names for Zdansky, 1928, or Kowalskia from the Pliocene (Zheng rat-like hamsters into 2 groups; the “little hamsters” 1984). Tscherskia occupied Europe prior to the Early ( Cricetulus ) with long tail but short hind-foot included Pleistocene and was present in Asia east of the Baikal triton and kamensis (now in Urocricetus ); nestor and arenosus Region ever since the Early Pleistocene (Gromov & were in a group characterized by long hind foot. Baranova 1981). The extinct Tscherskia rusa Storch, 1974, which is known only from the Holocene of Howell (1929) and after him Argyropulo (1933b, c) downgraded Tscherskia to a subgenus of Cricetulus and this picture neatly. Bastam (north-west Iranian Azerbaijan), does not fit their view persisted in the mainstream taxonomic by having a smaller dorso-temporal vacuity, a T. rusa differs from the extant T. literature for the rest of the century (Corbet & Hill smooth coronal suture (square-edged in triton T. triton), a 1980, 1986, Honacki et al. 1982, Kowalski 2001). Tokuda (1941), however, restored the generic status of proodont incisors, decidedly shorter nasals, triangular interparietal (hexagonal in T. triton), a clearly Tscherskia which started to be accepted in 1950s, proportionally small coronoid process and a large particularly by students of hamsters’ karyology (Makino angular process. 1951, Won 1961, Kartavtzeva et el. 1980, Kartavtseva & Alekseeva 1987) and gained general credit in the was treated as a monospecific genus (or Tscherskia 1980s (Gromov & Baranova 1981, Vorontsov 1982, subgenus) in the majority of taxonomic works (e.g. Kostenko 1984, Pavlinov and Rossolimo 1987). Some Allen 1940, Ellerman 1941, Corbet 1978, Wang 2003). authors, the Chinese in particular, continued to classify As an exception, Tate (1947) recognized 3 species Tscherskia as a subgenus of Cricetulus well into the 1990s ( triton , nestor and arenosus ). Vorontsov & Radjabli (1969), (Corbet & Hill 1992, Li & Wang 1996, Zhang et al. who misinterpreted supernumerary B chromosomes as 1997) and even after 2000 (Luo et al. 2000, Chen et al. a trait of taxonomic importance, linked different SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 31. chromosomal numbers with species names: triton (2n = Key to species 30) and albipes (2n = 28); their proposition was refuted by Kartavtseva et al. (1980). Gromov & Erbajeva (1995) 1a) Dorsal pelage blackish-brown; feet white; sagittal still regarded T. albipes as a species in its own right. A 2- suture longer than the width of parietal; incisive species taxonomy as adopted in this volume follows foramina longer, their posterior margin terminates Jiang et al. (2024) with nomenclatural amendments. just anterior to the M1 level (Figure 26); present in western Henan (west of 112th meridian) and Argyropulo (1933b, c) relegated Cansumys canus to a southern Shaanxi (south of 34.5th parallel) (Figure subspecies of the common rat-like hamster, which 28) ………………………………………. collina persisted in the literature until Ross (1988) showed that 1b) Dorsal pelage buffy-grey or drab-grey; feet Cansumys and Tscherskia are distinct genera (see under frequently with dusky ankles and proximal Cansumys). Irrespective of this, some authors metatarsal area (Figure 25); length of sagittal suture synonymized ningshaanensis with Cansumys canus (e.g. approximately equals width of parietal; incisive Zhang et al. 1997, Wang 2003, Liao et al. 2007). Song foramina shorter, their posterior margin (1985) named ningshaanensis as a subspecies of triton terminates well in front to the M1 level (Figure 26); diagnosing it by an extensive white tail tip (tail is the only rat-like hamster throughout much of the uniformly dark in Cansumys). Musser and Carleton generic range; in Henan present east of 111th (2005: 1041) stressed that molar tooth-row in meridian, in Shaanxi present north of 34.5th ningshaanensis (= 4.7–5.7 mm) is of same length as in parallel (Figure 23) ………………….….…. triton triton and decidedly shorter than in Cansumys canus (= 6.4–6.6 mm). Jiang et al. (2024) provided molecular Tscherskia triton (Winton, 1899) – evidence showing that ningshaanensis was part of Common Rat-like Hamster Tscherskia and distinct from Cansumys. Characteristics Cricetus (Cricetulus) triton Winton, 1899: 575. Not “de . Tscherskia differs clearly from the remaining Cricetina morphologically (Ross 1992), Winton and Styan” (Lee et al. 2014: 167). Type chromosomally (Romanenko et al. 2007), and locality: “N[orthern] Shantung [Shandong]”, China. genetically (Lebedev et al. 2003, 2018a, Neumann [Cricetus (Urocricetus)] triton: Trouessart, 1904: 395. Name 2007). Ross (1992) diagnosed the genus by the (1) combination. presence of 5 saccular dilatations ( Cricetulus nestor Thomas, 1907: 466. Type locality: “Kim- ampullae colli ) associated with caecum (cf. Figure 127 in Vorontsov hoa [Gimhwa], 65 miles [105 km] N.E. [north-east] 1967), (2) a square-edged coronal (fronto-parietal) of Seoul, 300’ [914 m]”, South Korea. suture, and by (3) occasional presence of Cricetulus triton: Thomas, 1908b: 9. Name combination. supernumerary (B) chromosomes (which were never Cricetulus triton incanus Thomas, 1908a: 45. Type locality: reported in other Cricetinae). In addition, “Near Ko-lan-chow, Shan-si”; emended to “12 Tscherskia shows (4) a weakly developed semilunar sulcus on the miles N.W. [north-west] of Ko-lan-chow [Kelan], tongue (absent in Shan-si [Shanxi]. 7000’ [2,134 m]” (Thomas 1908b: Cricetulus and Nothocricetulus ), (5) well- developed 974). torus linguae (weak in Cricetulus and Nothocricetulus Tscherskia albipes Ognev, 1914: 103. Type locality: ), and (6) longer median sulcus (shorter in Allocricetulus “долина р. Туманъ-ганы (Туманъ-ула), граница ). Glandular and corneous epithelium of stomach are of about equal extent, while in Российской Имперiи и Кореи”; in German Cricetus and Allocricetulus summary (p. 125): “sandige, durch Graswuchs the corneous epithelium extends into the glandular portion. In comparison to befeistige Dünen auf dem linken Ufer des Flusses Cricetus and Allocricetulus Tuman-Gan (im südlichen Teil des russischen , Tscherskia has shorter intestine relative to head and body length. Primorsky-Gebietes, in der Nähe der Grenze mit Korea).” Pavlinov & Rossolimo (1987: 170) give the type locality as: “Приморский кр., р. Тумыньцзян”, i.e. Primorskiy Krai, Tymyn’tszyan [Tumannaya] River, Russian Federation. 32 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Cricetulus triton nestor: Howell, 1929: 50. New rank for T[scherskia] t[riton] incana: Shenbrot, 2017e: 285. Change n estor. of extension for gender agreement. Cricetulus triton fuscipes G. Allen, 1925: 5. Type locality: Cricetulus triton nester: Jo, Baccus & Koprowski, 2018: “Peking [Beijing], Chili [Zhili] Province [Beijing 169. Incorrect subsequent spelling of nestor Thomas. Province], China.” Asiocricetus bampensis Kishida, 1929: 148, 150. Type Etimology. Tscherskia is eponym for Aleksandr locality: Bam-po (also Bampo or Man'po), Kankyo- Ivanovich Cherskiy (Александр Иванович Черский hokudo (north Hangieng), 50 feet (15 m), South [Russian]; 1879—1921), a Russian naturalist who made Korea (cf. Kuroda 1934: 231, Jones & Johnson his name in zoological explorations of the Russian Far 1965: 370). East, and in September 1913 collected the type series of Asiocricetus yamashinai Kishida, 1929: 156. Type locality Tscherskia albipes (Borissenko et al. 2001: 198). Cherskiy is the same as for bampensis; the two taxa were based has species group eponyms in mammology, on vouchers belonging to different age groups: the ornithology, ichthyology and entomology (as czerskii adult individual was named as bampensis and the and tscherskii). The meaning of the species epithet triton subadult one as yamashinai (see Kuroda 1934: 232). is less clear. In Greek mythology, Triton was a God of Cricetulus (Tscherskia) triton: Argyropulo, 1933b: 247. the Sea and is frequently portrayed with a human head Name combination. and torso and a long fish tail; triton is thus possibly in [Cricetulus (Tscherskia)] triton nestor: Argyropulo, 1933b: allusion to the tail which is proportionally longer in 149. Name combination. Tscherskia than in any other hamster known to Winton. [Cricetulus (Tscherskia)] triton incanus: Argyropulo, 1933b: 149. Name combination. Common name for Tscherskia, which is in prevailing use, [Cricetulus (Tscherskia)] triton fuscipes: Argyropulo, 1933b: is a greater long-tailed hamster. We reinstall here a rat- 149. Name combination. like hamster, which was frequently used in the past: Cricetulus arenosus Mori, 1939: 21 (Japanese text) & 64 “hamster rat” (Sowerby 1923), giant rat-headed hamster (English text). Type locality: “Tung-liao [Tongliao], (Loukashkin 1944) or “rat-like hamster”; the latter is North-East of Jehol”, Nei-Mongol, China. English translation of “Крисовидный хомяк” Cricetulus triton bampensis: Ellerman, 1941: 435. Name [Russian] and Rattenähnliche (or Rattenartige) Hamster combination. [German]; Ognev 1914, Flint 1966b). Cricetulus triton yamashinai: Ellerman, 1941: 435. Name combination. Distribution. The range covers an estimated 1,632,084 Tscherskia triton: Tokuda 1941: 36. First use of the km2 in eastern Asia between the 100th meridian and the current name combination. shores of the Sea of Japan and the Yellow Sea (Figure Asiocricetus hampensis: Tate, 1947: 257. Incorrect 23). The great majority of the range is in China in the subsequent spelling of bampensis Kishida. provinces of Heilongjiang, Jilin, Liaoning, south- Tscherskia triton albipes: Kartavtseva & Alekseeva, 1987: eastern Nei Mongol, Beijing, Hebei, Tianjin, Shandong, 97. Name combination. Jiangsu, Anhui, Henan, Shaanxi (north of the Wei-He Tscherskia triton arenosus: Kartavtseva & Alekseeva, 1987: River), Shanxi, Ningxia, Zhejiang, and south-western 97. Name combination. Gansu (cf. Jiang et al. 2015, 2024). The most obvious Tscherskia triton nestor: Ross, 1992: 104. Name distributional gap in China coincides with the Ordos combination. Plateau and very few records are situated on the left Tscherskia triton fuscipes: Ross, 1992: 105. Name bank of the Yellow (Huang He) River to the west of the combination. Ordos Loop in the Helan-Shan Mts. The south-western Tscherskia triton incanus: Ross, 1992: 105. Name range transgresses the Yangtze River in Anhui and combination. Jiangsu, reaching the extreme northern Zhejiang. The T[scherskia] (Cricettilus) triton: Borisov, 2012: 541. common rat-like hamster is seemingly widespread in Incorrect subsequent spelling of Cricetulus in the Korean Peninsula, and reaches in the north the combination with triton. southern Primorsky Krai of the Russian Far East up to Khanka Lake and the upper part of Ussuri River valley. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 33. Figure 23: Distributional range of the common rat-like hamster Tscherskia triton. It occupies several islands, including Putyatin Is. in the 1936, Jo et al. 2012). Elevational range is from sea level Strelok Bay, 1.5 km offshore the mainland Russian up to 2,827 m (mean elevation = 532 m). Primorye, and Jeju (Cheju) Is. (Jones & Johnson 1965) 83 km off the nearest point on the coast of South Characteristics. A moderately large hamster of rat-like Korea. The species was also recorded on an unnamed external appearance (Figure 24). In contrast to the island on the upper Razdolnaya (Suyfun) River in the brown rat of comparable size, the rat-like hamster has Oktyabrskiy Rayon (Primorsky Krai). smaller feet and shorter tail, both absolute and relative to head and body. The tail is comparatively long, Within the majority of its range, T. triton is one of the accounting for 40–74% (usually 45–57%) of head and most widespread small mammals. It is common in body length. Ears protrude well above the fur and the many places and can be locally abundant. The species is eyes are of normal size. Dimensions: body mass = 80– catholic in habitat preferences, occupying cultivated 285 g, length of head and body = 135–223 mm, length areas (particularly rice fields) as well as abandoned of tail = 65–110 mm, length of hind foot = 22–29 mm, farmland, dry hillsides covered with grass or scrub, length of ear = 17–23 mm, condylobasal length of skull dense bushes, grassy lowlands, coppices, coniferous = 34.6–46.0 mm, zygomatic width = 16.0–26.3 mm, plantations and woodlands (Won 1961, Jones & length of maxillary tooth-row = 4.9–6.5 mm. Secondary Johnson 1965, Luo et al. 2000). Preferred are uplands sexual dimorphism in size is weakly expressed or absent and upper edges of ravines (Kostenko 1984, Shenbrot (Li et al. 1990). As typical of hamsters, the feet are 2017e). On the Jeju Is. and in the Ussuri Region rather short. There are 5 toes on front and back feet; (Primorsky Krai), common rat-like hamsters inhabit the small front thumb is equipped by a claw and is humid to damp places inside shaded forests (Zolotarev shifted posterior. Palms have 5 pads and soles have 6 pads each. Interdigital palmar pads are of about same 34 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 24: Common rat-like hamster Tscherskia triton from Primorsky Krai, south-eastern Russian Federation. Note the white-tipped tail and dusky proximal metatarsals. Photo courtesy of Irina V. Kartavtseva. size as metatarsal pads; the plantar pads are large and bases below the white tips. A white throat patch of closely packed together (Mori 1930). The fur is soft and irregular shape is usually present, with hairs white to the silky, at least in some populations. Dorsal hairs are 11– bases. Upper lips and chin are pure white. Demarcation 15 mm long, interspersed with sparse all-black or dark- on the flanks is either blurred or sharply defined. brown stiff hairs which stick out by 3–4 mm. Vibrissae are short. Females have 8 nipples (Ognev 1914). General colour is buffy-grey or drab-grey and varies from pale buffy-grey to smoke-grey without the buffy shade. The colour depends on the locality and is usually uniform within the same population. Difference in overall colour of the pelage is due to the length of ochraceous-buff or beige terminal band of hairs and the number of all-dark stiff hairs (Ross 1992). Fur is darker on the dorsal line, which is mixed to a greater extent with all-black or black-tipped hairs; there is, however, no distinct streak. The posterior back is darkened in some populations. Underside ranges from white or greyish-white to dull grey, which is only slightly lighter Figure 25: Dorsal side of hind foot in Tscherskia triton. Note that the than the back. This depends on the extent of slaty hair proximal ½ of the metatarsal region of the foot is dusky. The voucher is from Ussuriysk, Russian Far East. Photo B. Kryštufek. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 35. Figure 26: Skull and mandible in rat-like hamsters Tscherskia. Top to bottom: T. collina and T. triton nestor (Primorsky Krai, south- eastern Russian Federation). Juveniles are uniformly slaty-grey and nearly without The skull is of similar shape as in Cricetulus and brownish wash above; their underside is slaty and less Nothocricetulus, but is more stoutly built (Figure 26). tipped whitish than in adults (Kuroda 1939). The paws Adult skulls are clearly ridged on the frontals and show are pure white, though the proximal metatarsal area and medial (interorbital) groove; the ridges are weak on the the ankles are dusky (fuscous) in some populations parietals but reach the lambdoidal crest. Zygomatic (Figure 25), particularly in the northern part of the arches are moderately expanded (zygomatic width range. Ears are thinly covered with short dull brown accounts for 56–61% of condylobasal length) and the hairs except for the extreme rim which is white. dorsal profile is evenly though moderately bowed. The Vibrissae are blackish brown or whitish. Tail is thinly rostrum is heavy; its breadth across the capsular covered with short hairs which leave the underlying projection of the upper incisors (the nasolacrimal annulation exposed; dorsal side is blackish brown, dark capsule) exceeds the interorbital width. The nasals are brown to dusky and the ventral side is greyish or narrow and long with a pointed apex; posterior whitish. The terminal tip is frequently beige or white, premaxillary process extends into the maxillary region usually for < 5 mm. 36 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 27: Grinding pattern of upper (a, b) and lower (a’, b’) molars in common rat-like hamster Tscherskia triton from Primorsky Krai, Russian Federation (a) and Jilin Province, China (b). Lingual is to the left; scale bar = 1 mm. beyond the naso-frontal suture. The coronoid (fronto- and 0.58–0.85–0.80 for mandibular row. Tubercles on parietal) suture is characteristically square-edged. M1–2 are of comparable size, however, the lingual pair is Parietals are rather small and the interparietal is usually slightly shifted posteriorly. Hypocone and metacone of hexagonal and extends across the greater part of the M3 are reduced and obviously smaller than the anterior roof of the cranium. The orbits give less rounded cones. The conulids of lower molars clearly alternate appearance than in Cricetulus; bullae are large, inflated and the labial ones are shifted posteriorly; the and of oval shape; subsquamosal foramen is small and anteroconulids of M1 which are of comparable size, not visible in dorsal view; stapedial and sphenofrontal form a transverse crescent. foramina are present; pterygoid fossae are deep. Masseteric plate is rather broad with a straight or Glans penis is ~5.5 mm long, and ~2.9 mm deep; it is slightly concave anterior margin. Paroccipital process is urn-shaped and therefore broader distally (~3.9 mm) well developed and is shifted towards the occipital than basally (width at the lining of prepuce ~2.8 mm). condyle. Incisive foramina are of normal size, only Dorsal papilla is prominent and divided into 5 lobes; rarely reaching the level of cheek teeth; the hard palate lateral papillae are narrower and shorter than the central margin is at the level of the posterior edge of M3. In papilla; all these papillae project beyond the annular dorsal plane, the occipital condyles project beyond the fold and are visible from the outside (Tokuda 1941). occiput. Mandible is comparatively low and long; a Ventral papilla bifurcates apically; it is of about the same sickle-shaped coronoid process is large and the size as papillae laterales, and is hidden by the expanded remaining processes are of moderate size. ventral rim of meatus urinarius. The epidermal spines cover the entire glans; they are smaller on the anterior The incisors are orthodont and coated with pale-to- surface of the glans and obviously larger on the dark orange enamel. In both rows (maxillary and proximal dorsal side. The baculum consists of proximal mandibular), the molars gradually decrease in size in stalk and distal trident; digits are not fused; the central anterior-to-posterior direction; M1 is relatively the distal digit (length ≈ 70% of the proximal baculum) is longest molar (Figure 27), M1 is relatively the slenderest longer than lateral digits. Shaft of the proximal baculum and the posterior two molars are comparatively the is slender, and the manubrium is laterally expanded, broadest. Relative molar length (M1-M2-M3) is 0.41– though still weak (Figure 17c); width across manubrium 0.31–0.28 for the maxillary row and 0.38–0.32–0.30 for is less than the length of the distal trident (Tokuda mandibular row; relative width of molars 1941). Ossification of the lateral digits is postponed (width/length) is 0.65–0.92–0.90 for the maxillary row (Vorontsov 1982). SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 37. Karyotype: 2n=28; 11 pairs of acrocentric and 2 pairs continuity of range make it unlikely that really discrete of metacentric autosomes (NFa=30). Of the sex races exist.” chromosomes, the X is large subtelocentric or submetacentric and the Y is metacentric or Ross (1992) reassessed the validity of subspecies by submetacentric of average size (Tsuchiya & Won 1976, using multivariate analyses of linear craniodental Kartavtzeva et al. 1980, Wang et al. 1999). In diakinesis, measurements. She concluded that nestor was the only the heterosomes pair side by side (Ross 1992). In subspecies of common rat-like hamsters deserving contrast to the remaining Cricetinae, Tscherskia shows recognition, in addition to the nominal subspecies triton. extensive intra- and extra-chromosomal Her study, however, remained uniformly ignored and rearrangements (Romanenko et al. 2012) and is the only we resuscitate it here by classifying the common rat-like true hamster with supernumerary (B) chromosomes. hamsters into the northern (nestor) and the southern The earliest reported karyotype showed diploid number (triton) subspecies groups based on cranial traits 2n = 30 due to the presence of 2 B-chromosomes exposed by Ross (l. c.). The latter group is further split (Makino 1951). So far, 1–2 B chromosomes have been into 2 subspecies (triton and incana) as they were reported and the proportion of somatic cells carrying recognized by earlier authors (Allen 1940, Luo et al. supernumerary chromosomes varied slightly between 2000). Differences in colouration are due to the length studies: 34.9–55.9% in the Russian Far East (Borisov of the buffy subterminal band and the number of longer 2012) and 67.5% in the Shandong Province, China all-brown hairs (Ross 1992). Colour reflects differences (Wang et al. 1999). Diploid number in individuals with in climate and substrate with pale hamsters occupying B-chromosomes is 2n = 28–30 (Russia) and 2n = 28– arid regions and dark hamsters being present in humid 29 (China). The proportion of individuals with B climate. chromosomes in 2 samples from the Russian Far East was 10.3% (n = 39; Kartavtzeva et al. 1980) and 11.1% Tscherskia triton fuscipes G. Allen is usually recognized as (n = 45; Borisov 2012). Wang et al. (1999) detected a subspecies in its own right (Allen 1940, Luo et al. supernumerary chromosomes in Shangdong but not in 2000, Wang 2003, Smith & Hoffmann 2008, Shenbrot Jilin and Shaanxi. Tscherskia triton differs from the 2017e), but this requires clarification. Subspecies fuscipes remaining hamsters in having large C-positive is diagnosed by dusky (fuscous) tarsal joint and the heterochromatin blocks in the centromeric region of 11 proximal ⅓–½ of the metatarsals which are normally autosomal pairs and the pericentromeric region on both white in the majority of hamsters. Dusky ankles, sex chromosomes (Borisov 2012, Kamimura et al. however, were observed also in other races (triton and 2022). nestor; cf. Howell 1929), and Allen (1940: 770) himself noted that “the form [fuscipes] is not a strongly marked Variation and subspecies. In the literature, the one.” The range of fuscipes is usually given as the entire common rat-like hamster is invariably reported as a north-east China (Beijing, northern Hebei, polytypic species and since the revision by Argyropulo Heilongjiang, Jilin, Liaoning, eastern Nei Mongol; Luo (1933b, c) 5 subspecies were recognized by the great et al. 2000, Wang 2003, Shenbrot 2017e) though the majority of authors. Ellerman (1941) listed 8 subspecies eastern border against T. t. nestor remains unresolved. and Chinese authors, who frequently omit nestor from Rat-like hamsters from the extreme north-eastern their lists of Chinese mammals, recognized 4 subspecies China (Provinces of Heilongjiang and Jilin), the entire in the country (e.g. Luo et al. 2000, Wang 2003); Smith Korean Peninsula and the Russian Far East are cranially & Hoffmann (2008) accepted for China also nestor, while those from Tianjin and the entire ningshaanensis as a subspecies in its own right, which we Shandong, as well as the topotypes of fuscipes from synonymize with T. collina (see under that species). Beijing, are cranially triton (Ross 1992). Corbet (1978: 92), however, was sceptical over the validity of so many infraspecific taxa stating that “the Phylogeographic structure is known only from a limited very slight differences involved [between populations] geographic sampling and therefore provides little the amount of intergradation and the apparent information for testing subspecific taxonomy. So far, 3 phylogeographic lineages are known from the mainland 38 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. (Xie & Zhang 2005b, Sheremetyeva et al. 2017). The between local populations occupying the Shandong Northern lineage is allopatric in the Russian Far East Province. and adjacent China. Further two lineages (the Central and the Southern, sensu Sheremetyeva et al. 2017) Tscherskia triton incana widely overlap in the North China Plain (Provinces of (Thomas, 1908) Beijing, Hebei, and Henan) and occupy both banks of the Yellow (Huang He) River. In phylogenetic trees constructed from mitochondrial and nuclear genes Synonyms. Cricetulus triton fuscipes G. Allen, 1925, (Jiang et al. 2024), Cricetulus arenosus Mori, 1939. arenosus, fuscipes, incana , and topotypical triton from the Shandong Peninsula clustered together, though the Shandong samples hold Taxonomy. In Allen’s view (1940: 771), incana is “a independent position in the cytochrome barely distinguishable race” and the difference in fur b tree. Genetic colouration against the nominal subspecies is slight diversity is comparatively high in all populations studied (Howell 1929). so far (cf. Xie & Zhang 2005a). Karyology also provides no evidence that would be useful in subspecies Etymology. The subspecific epithet incana is Latin for al. 1999). ‘light-grey’ in allusion to the fur colouration. delimitation of the common rat-like hamster (Wang et Subspecies group Characteristics. Mean values for 3 external and 2 triton craniodental traits (n = 4–7): body mass = 68.5 g, length of head and body = 150 mm, length of hind foot = 23.7, Distribution. Southern part of the rat-like hamster condylobasal length = 37.5 mm, length of maxillary range, tentatively southward of the 40th parallel. tooth-row = 5.41 mm. Tail is moderately long; its length accounts on average for 56% of head and body length. Characteristics. Usually smaller and of lighter colour. Fur is paler (drab-grey) than in other races of the Palate and rostrum narrower, diastema shorter, common rat-like hamster; the head and front back are posterior margin of incisive foramina terminates just pale grey. 1 anterior to the M level, shape of coronal suture rounded. Distribution. Arid habitats at the edge of the Ordos Tscherskia triton triton Plateau and eastward and southward of the Mu Us (Winton, 1899) Desert in western Shanxi (Kelan), northern Shaanxi, eastern Gansu, Ningxia, and south-central Nei Mongol; Distribution. China, tentatively between the 40th present on both banks of the Yellow (Huang He) River. parallel and the Yangtze River and eastward of about This is a rare subspecies occurring at low population the 110th meridian (cf. Luo et al. 2000). The subspecies densities (cf. Howell 1929, Allen 1940). was reported for the following provinces: Hebei, Beijing, Jiangsu (Xuzhou), Henan (Linxian), Shanxi Subspecies group nestor (Taiyuan and Lishi), Shaanxi (central Guanzhou Plain), Anhui and northern Zheijiang (Wang 2003). This group contains a single subspecies. Characteristics. Mean values for 3 external and 2 Tscherskia triton nestor craniodental traits (n = 21): body mass = 81.7 g, length (Thomas, 1907) of head and body = 142 mm, length of hind foot = 24.1 mm, condylobasal length = 33.3 mm, length of maxillary tooth-row = 5.37 mm (Luo et al. 2000). Tail Synonyms. Tscherskia albipes Ognev, 1914; Asiocricetus is comparatively short and on average accounts for 49% bampensis Kishida, 1929; Asiocricetus yamashinai Kishida, of head and body length. Pelage is smoke-grey; the head 1929. and front back are dark grey. Ross (1992) exposed Etymology. In Greek mythology, Nestor of Gerenia differences in fur texture and pelage colouration was a legendary king of Pylos (Peloponnese, Greece) SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 39. and a prominent secondary character in Homer’s Iliad Distribution. Northern part of the common rat-like and Odyssey. He is described as a large, wise, grey- hamster range, tentatively northward of the 40th parallel. haired elderly warrior. Though Thomas did not explain Present in Russian Far East (Primorsky Krai), his choice of the name, he perhaps alluded on a large throughout Korea and in north-east China size of nestor, which was in his time “by far the largest (Heilongjiang, Jilin, Liaoning, eastern Nei Mongol, known [sub]species” of common rat-like hamsters north Hebei). (Thomas 1907: 466). The grey fur of nestor, which contrasted more buffy hair in the nominal subspecies, Characteristics. On average larger and darker than the may also play a role in selecting the name. triton subspecies group. Mean values for 3 external and 2 craniodental traits (n = 59–75): body mass = 116.1 g, Taxonomy. The nestor of Thomas is the 2nd oldest length of head and body = 162.5 mm, length of hind species-group name in the genus. It was ranked in the foot = 25.2 mm, condylobasal length = 37.2 mm, length past either as a species in its own right (Allen & of maxillary tooth-row = 5.5 mm. The tail is Andrews 1913, Sowerby 1923, Kishida & Mori 1931, comparatively short and accounts on average for 49% Tate 1947) or a subspecies of triton (Howell 1929, of head and body length. Dorsal fur is frequently dark Argyropulo 1933b, c, Kuroda 1934, and subsequent grey, occasionally almost blackish, without the buffy or authors). This is the only subspecies listed for Korea clay-coloured shade. Underside is usually greyish white (e.g. Allen & Andrews 1913, Jones & Johnson 1965, and the slaty bases of the hairs are exposed below their Won 1968, Jo et al. 2018) and for the Russian part of white tips; the pectoral spot of irregular shape is white the species’ range (Argyropulo 1933b, Gromov et al. to hair bases. Summer pelage is darker than winter 1963). Chinese authors, on the other hand, frequently pelage. Tail tip is white for ~10 mm, rarely more (up to ignore nestor and classify common rat-like hamsters 50 mm; Zimmermann 1964). Palate and rostrum are from north-western China as fuscipes with arenosus as its broader than in the triton subspecies group, diastema is synonym. longer, posterior margin of incisive foramina terminates well before the M1 level, and shape of coronal suture is Kartavtseva & Alekseeva (1987) elevated both, albipes square edged. and arenosus, to subspecies in their own right, justifying this decision by size differences. Size, however, varies Tscherskia collina (G. Allen, 1925) – in nestor even within the Korean Peninsula; e. g. Tsinling Rat-like Hamster specimens in northern parts are on average smaller than those occupying central regions of the Peninsula (Jones & Johnson 1965). Cricetulus triton collinus G. Allen, 1925: 5. Type locality: “base of Tai-pei-shan, Tsing-ling [Tsinling] Based on 2 skulls from Jeju Is., Jones & Johnson (1965) Mountains, Shansi Province, China.” ‘Shansi’ (now Shanxi) is obviously incorrect spelling for “Shensi” stressed the differences between this insular population (now Shaanxi) ( cf. Howell 1929: 49, Allen 1940: 771). and its mainland counterparts. The Jeju skulls were We therefore place the type locality of collina in narrower, with not so well-developed supraorbital Shaanxi. ridges, more evenly rounded bulla, shorter incisive [Cricetulus (Tscherskia)] triton collinus: Argyropulo, 1933b: foramina and paler enamel on the upper incisors. 149. Name combination. Analysis of 2 partial mitochondrial genes retrieved Cricetulus triton meihsienensis Ho, 1935: 288. Type locality: moderately deep genetic divergence (> 3.5%) between Meihsien [Mian Xian], Shensi, China (Allen 1940: the Jeju and the mainland common rat-like hamsters 771). (Koh et al. 2013). In their overall size, the Jeju hamsters Cricetulus triton ningshaanensis Song, 1985: 137. Type do not differ appreciably from the grand mean for the locality (in English summary, p. 139): “Ningshaan subspecies (see below). Means for the Jeju sample (n = district [Ningshan County] (alt. 1050 m), Shaanxi”, 14) are: body mass = 114.6 g, length of head and body China. = 175.0 mm, length of hind foot = 25.6 mm (Park & Tscherskia triton collinus: Ross, 1992: 105. Name Oh 2017). combination. 40 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. C[ansumys] c[anus] ningshaanensis: Lu & Wang, 1996: 121. synonymize ningshaanensis with collina. This follows Luo Name combination. et al. (2000: 72); meihsienensis was regarded as junior C[ricetulus] c[anus] nighshaanensis: Zhang, Jin, Quan, Li, synonym of collina already by Allen (1940: 771). Ye, Wang & Zhang, 1997: 216 (Chinese) & 217 (Eng.). Incorrect subsequent spelling of Lu & Wang (1996) classified ningshaanensis as a ningshaanensis Song. subspecies of Cansumy canus, which remained the Cansumys canus ningshanensis: Wang, 2003: 166. Incorrect prevailing view for the rest of the century (Zhang et al. subsequent spelling of ningshaanensis Song. 1997, Luo et al. 2000, Wang 2003); ningshaanensis was T[scherskia] t[riton] collina: Shenbrot, 2017e: 285. Change again synonymized with Tscherskia triton by Musser & of extension for gender agreement. Carleton (2005). Ross (1992) maintained very different Tscherskia ningshaanensis: Jiang, Wang, Yang, Pan, Liu & view on this issue; on the one hand she overlooked Lu, 2024: 1231. New rank for ningshaanensis. ningshaanensis and on the other hand classified collina and meihsienensis as synonyms of the nominotypical Etymology. The specific epithet “collinus” (collina) is subspecies T. t. triton. Latin for ‘hilly’ in allusion to its habitat in “the hills of southern Shansi and Shensi” (Allen 1925: 5). Adjective Distribution. Range covers an estimated 55,563 km2 in in the common name alludes to Mt. Tsinling (Qinling) southern Shaanxi to the south of Wei-He River valley, within the range of the species. and western Henan (Figure 28). Identical range was defined already for subspecies collina (Allen 1940: Figure Taxonomy. Based on deep molecular divergence 28 on page 766). Occupies warm and humid forests in separating triton proper and ningshaanensis (K2P = a hilly countryside at elevations between 475 and 2,470 15.1%, i. e. 3.88 Mya), Jiang et al. (2024) classified these m (mean = 1,110 m). taxa as distinct species of rat-like hamsters Tscherskia. Figure 28: Distributional range of the Tsinling rat-like hamster Tscherskia collina. Two names (collina and meihsienensis) from the Tsinling Characteristics. Similar to T. triton but on average Mts., however, antedate ningshaanensis, and Jiang et al. (l. smaller. Dimensions: body mass = 38–93 g, length of c.) sequenced hamsters from none of them. Given the head and body = 112–185, length of tail = 72–114 mm, proximity of their type localities, we tentatively length of hind foot = 23.5–27.0 mm, length of ear = SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 41. 20–24 mm, greatest length of skull = 29.3–37.5 mm, le même genre”). By using a diminutive for Cricetus, zygomatic width = 14.7–19.0 mm, length of maxillary Milne Edwards intended to stress the mutual tooth-row = 4.9–5.7 mm. The tail is comparatively “analogies” (“Pour rappeler ces analogies”) between the long, accounting on average for 60% of head and body large and the small hamsters. length. Dorsal fur is dark greyish-brown with ample blackish shade; all-black hairs are numerous and the Nomenclature. Recent literature usually hyphenates remaining hairs have broad beige subterminal band and the taxon-authorship name Milne Edwards, spelling it a minute black tip. Buff tint predominates on the side Milne-Edwards (e.g. Ellerman & Morrison-Scott 1951, of the head and body; demarcation line is blurred. The Corbet 1978, Pavlinov et al. 1995, Wilson & Reeder underside is dark grey grizzled by contrastingly white 2005, Pardiñas et al. 2017). This was not always so in hair tips; the chin and a small median spot on the throat the past. Some authors either used a hyphen (Trouessart are white to hair bases. Ears are thinly covered with 1897, Palmer 1904) or not (Palmer 1897, 1899), or were short blackish brown hairs; feet and ankles are whitish. inconsistent in this (Trouessart 1904). The composite The tail is all-blackish or indistinctly bicolour due to name Milne Edwards was created by Henri Edwards white hairs on the ventral side. Its distal portion is pure (1800–1885) who added one of his first names (Milne) white for the terminal 3–52 mm (Song 1985). The skull to the family name Edwards in order to be recognized is essentially as in T. triton with minor differences among all his relatives (he had 27, or perhaps 28, (Figure 26): palate and rostrum are narrower, diastema brothers and sisters) (Hansson not dated). Hansson is shorter, posterior margin of incisive foramina claimed that Henri (the father) usually did not use the terminates just anterior to the M1 level, supratemporal hyphen, while Alphonse (the son; 1835–1900) “always ridges are weaker, and the sagittal suture is longer. did”. Our search through contemporary literature Karyotype is as in T. triton; B-chromosomes were so far revealed inconsistency in this respect in both members not detected but the number of karyotyped animals was of the Edwards family. We therefore strictly adopted small (Wang et al. 1999). the spelling as it appeared in the title of the original publication. In the joint work by the father and son Variation and subspecies. The extent of terminal Milne Edwards (Milne Edwards & Milne Edwards white area on the tail varies among populations; it is 1868–1874), the hyphen was not used (see also Milne usually short (length = 3–10 mm) and occasionally Edwards 1871). covering 40–60% of the tail (Liang et al. 2024). The species is presumably monotypic. Taxonomy. Milne Edwards proposed Cricetulus as a GENUS: new genus (see also David 1871: 93), however, he Cricetulus A. Milne Edwards, himself downgraded it to a subgenus of Cricetus shortly 1867 – Lesser Hamsters afterwards (Milne Edwards 1871). In the early 1900s, several authors adopted Cricetulus as a genus in its own Cricetulus right (e. g. Trouessart 1904) which is still a practice. The A. Milne Edwards, 1867: 376. Not 1871 (Corbet & Hill 1992: 391). Type species by scope of Cricetulus, however, varied. For the greater part monotypy is of the 20th century, the name covered all current species Cricetulus griseus A. Milne Edwards, 1867 (cf. Palmer 1904: 203) of Cricetina except Cricetus, and all members of Urocricetini. Given the diversity of incorporated forms, Etymology Cricetulus was soon split into subgenera. Argyropulo . Cricetulus is diminutive of Cricetus, which is the name for hamsters (Palmer 1904: 203). Milne (1933b, c) recognized 3 subgenera: Tscherskia (with Edwards (1867: 375–376) who coined the name Cansumys), Allocricetulus, and Cricetulus s. str. The latter Cricetulus included migratorius (now in Nothocricetulus) and the , stressed that small hamsters of China, although externally resembling arvicolines, actually current Urocricetus. Argyropulos’ classification was possess cheek pouches and display molar morphology retained in major revisions which emerged around 1950 typical of hamsters, yet still cannot be classified “in the (Allen 1940, Ellerman 1941, Kuznetzov 1944, same genus” with Bannikov 1954, and Ellerman & Morrison-Scott 1951). Cricetus (“ils se rapprochent donc des Hamsters, sans cependant pouvoir prendre place dans Flint (1966b) was perhaps the first to restrict Cricetulus 42 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. to its current scope, although with the inclusion of approaches the orbit and restricts the squamosal suture Urocricetus and Nothocricetulus, while Ross (1982) (sutura squamosa cranii) (Figure 34); in Nothocricetulus, the extracted Urocricetus from Cricetulus. Taxonomic squamosal suture is longer and the fronto-temporal solutions proposed by Flint and Ross were regrettably angle does not approach closely the orbit (Figure 48). overlooked and Cricetulus continued to serve as collective name for species that are now in 5 Distribution. East Asia between the 70th meridian in independent genera: Urocricetus, Tscherskia, Cansumys, the west and the Sea of Japan and the East China Sea in Nothocricetulus, and Allocricetulus (Wang & Cheng 1973, the east. Northern border is on the upper reaches of the Corbet 1978, Corbet & Hill 1980, 1986, Honacki et al. Irtysh, Ob, Yenisei, Angara, and Lena Rivers, the 1982, Zhang et al. 1997, Luo et al. 2000). The species of Baykal Lake and the Amur Valley; usually the range Urocricetus and Nothocricetulus were retained inside does not surpass the 55th parallel. The southern border Cricetulus until very recently (Musser & Carleton 2005, tentatively coincides with the line estuary of the Smith & Hoffmann 2008, Lebedev 2012, Jiang et al. Yangtze to the upper reaches of the Yangtze, Mekong 2015, Pardiñas et al. 2017), until removed from its scope and Salween. by Lebedev et al. (2018a). Currently, 6 species are listed inside Cricetulus (Pardiñas et al. 2017), and this number was similarly high (around 5 species) in the 1990s (see under C. barabensis). Based on multigene phylogenetic analysis, Cricetulus holds basal position to a clade consisting of Nothocricetulus + Allocricetulus + Cricetus (Neumann et al. 2006, Lebedev et al. 2018a). Similar analyses, which used morphological and / or chromosomal markers, failed in confirming monophyly of Cricetulus (Ross 1992, Romanenko et al. 2007) or placed it in a sister position against N. migratorius (Potapova 2005) (Figure 1). The divergence time between Cricetulus and the clade consisting of Nothocricetulus + Allocricetulus + Cricetus (the Cricetus clade) was estimated at 5.61 Mya (CI = 4.43– 6.99 Mya) (Lebedev et al. 2018a), which is a close match to 4–6 My old fossils from the Early Pliocene of China (Lindsay 1994). The entire Cricetus-clade is heterogenous, therefore Cricetulus differs from Cricetus and Allocricetulus in many aspects of external and cranial morphology. On the other hand, Cricetulus resembles Nothocricetulus in external appearance and cranial morphology. The following traits differentiate well between the two genera: (1) in Cricetulus the baculum has a long trident, which is of approximately same length as the proximal baculum (Figure 17d); trident is Figure 29: Tail in Cricetulus barabensis (a), C. sokolovi (b), C. rudimentary in Nothocricetulus (length of trident equals longicaudatus (c), and Nothocricetulus migratorius (d). Specimens are of ~¼ that of proximal baculum) (Figure 17e); (2) M 1–2 comparable size. Scale bar = 10 mm. lack metalophule (the antero-lingual ridge of the hypocone; cf. Figure 35), which in Nothocricetulus Characteristics. Small hamsters with the tail shorter contributes to an X-pattern of enamel ridges between than ½ of head and body length; tail is tapering the medial and posterior pair of cusps; (3) the fronto- gradually from the broad base towards the tip (Figure temporal angle of the parietals (in dorsal view) 29a–c). Snout is pointed, eyes are rather large and ears SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 43. are long, delicate and rounded. Feet are shortened and 39 & 40); hair bases grey; soles hairy in winter, less adapted for burrowing than in Cricetus, toes are concealing the pads; number of chromosomal comparatively short; soles may be partly hairy. Fur is arms NF = 40; present in Mongolia, to the west of thick and soft; colour of the back varies from light the 113th meridian and to the south of the 46th greyish or buff, to dull grey-brown; belly is grey and in parallel, and in adjacent Nei Mongol (north of some taxa the hairs are white-tipped. Testicles of Ordos loop)1 …………........................….. sokolovi sexually active males are exceptionally large (Figure 2b) Dorsal fur usually intense reddish-brown or dark 39b); females have 4 pairs of nipples (exceptionally 5 grey; mid-dorsal stripe usually prominent and pairs; Zimmermann 1964). sharp (Figures 32, 36 & 37); hair bases slate; soles nude year-round, pads exposed and evident; The skull is of murine type and not much specialized. It number of chromosomal arms NF = 38; absent is comparatively shallow and narrow; zygomatic arches from parts of Mongolia and Nei Mongol1 account for 50–60% of condylobasal length. ……………………………….………. barabensis Condylobasal length is shorter than the profile length and occipital condyles are not visible in dorsal view 1 In Mongolia, the northern-most occurrence of C. sokolovi is at 46.5° and the (Figure 34). Rostrum is moderately long and braincase southern-most occurrence of C. barabensis is at 45.8° is large; frontals, parietals and occipitals are not ridged. Interorbital constriction is wide, and the interparietal bone is of broad diamond shape, unrestrained and expanding across the whole roof of the skull. The masseteric plate is relatively small with a straight anterior margin; it is invariably of the myomorphous type. Incisive foramens are as long as hard palate, approaching posteriorly the M1 level. The palate terminates behind the M3. Bullae are of moderate size and shifted well anterior of occipital condyles. Mandible shows no peculiarities. The upper incisors are than the incisive foramina. Diploid number of barabensis (left) and C. longicaudatus (right). Note that C. barabensis is equipped with a heavier ramus and more robust coronoid process. chromosomes is either 20, 22, or 24. orthodont to opisthodont; molars are decidedly shorter Figure 30: Superimposed outlines of mandibular ramus in Cricetulus Key to species SUBGENUS: Cricetulus A. Milne Edwards, 1867 1a) Dorsal side plain-grey with no dark spinal stripe; tail is long relative to body (usually >30% of head Taxonomy. The subgenus Cricetulus contains 2 species: and body length) and to hindfoot (> 1.95-fold the C. barabensis and C. sokolovi. For further details see the hindfoot length); skull is comparatively narrow; account on Ourocricetulus new subgenus. coronoid and articular processes are slim (Figure 30); the X chromosome is the largest element in Characteristics. Defined by mtDNA sequences the set …………………………......... longicaudatus (Lebedev et al. 2018a, Poplavskaya et al. 2018b). The X 1b) Dorsal side usually with a dark spinal stripe chromosome is of medium size (Orlov et al. 1978). (Figures 32, 36, 37, 39 & 40); tail is comparatively Mid-dorsal (spinal) stripe is nearly always present and is short (< 1.95-fold of hindfoot length); rostrum is usually well defined (Figures 32, 36, 37, 39 & 40); tail is comparatively broad; coronoid and articular rather short, accounting to 24–31% of head and body processes are robust (Figure 30); the X length (Figure 29a, b). Rostrum tends to be broader and chromosome is of medium size……………….. 2 zygomatic arches are more expanded than in 2a) Dorsal pelage usually light reddish-brown or light Ourocricetulus new subgenus; palate is broader, maxillary grey; mid-dorsal stripe obscure or absent (Figures tooth-row is shorter, and diastema is longer (Figure 34). 44 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. The coronoid and the articular processes of the from Suen-hoa-fu, near Kalang” (footnote in mandible are robust (Figure 30). The 2nd internal fold Chaworth-Musters 1933: 222) and erroneously fixed (if2) and 2nd primary fold (pf2) of M1 are separated by “Suenhoafu, near Kalgan, Mongolia” as the type metacone (Figure 35). locality. For reasons not explained, Allen (1940: 758) claimed that the type was from “the vicinity of Cricetulus barabensis (Pallas, 1773) – Peiping, Hopei, China”, which is in any case close to Striped Lesser Hamster Beijing. The correct type locality, however, is Beijing, China (e. g. Kuroda 1939: 23). Glis barabensis [correctly Pawlowsk = Pavlovsky District], near chinoise”. Chaworth-Musters (1933: 223) defined Barnaul, S.W. [south-western] Siberia” (Chaworth- the type locality as “Sartchy, Hoang-ho, inner Musters 1933: 223) in Altaysky Kray of Russian Mongolia”, now Linfen in Shanxi, China. For 1871 Federation. An earlier restriction of the type locality as the date of publication (instead of 1867, 1868, to “Irtish” (Thomas 1917: 452) is erroneous. 1868–1874, or 1874), see the account on Taxonomy : Erxleben 1777: 374. Name combination. below. Mus furunculus Pallas, 1779: 273. New name for barabensis Cric[etulus] obscurus: A. Milne Edwards, in David (1871: Pallas (Chaworth-Musters 1933: 221). Pallas 93). Name combination. renamed barabensis because Messerschmidt (quoted Cricetus mongolicus Mus barabensis Pallas, 1773: 704. Type locality: “in Accompanying illustrations (Plate 12: Figure 1; Plate Cricetus (Cricetulus) obscurus A. Milne Edwards, 1871: 136. arenoſis ad Ob fluuium, non longe ab argentaria a 13: Figures 2, 2, 2b, 2c) appeared in Milne Edwards fabrica quae S. Paulo nomen habet”; restricted to & Milne Edwards (1868–1874). Type locality is “Kasmalinskoi-Bor [Kasmalinskiy Bor], Pawloswk “Sartchy sur le bord du Hoangho, dans la Mongolie from Pallas 1779) used in 1742 furunculus (as name for Thomas, 1888: 134 (footnote). New “Dalai Nor” [Dalai Nur, Nei Mongol, China] (Pallas (Waterhouse, 1837), now Hesperomys obscurus 1779: 273, footnote). For more discussion, see Necromys obscurus (Akodontini, Sigmodontinae). Cricetulus barabensis griseus (below). [Cricetus (Cricetulus)] griseus: Furrunculus myodes) for a striped lesser hamster from Thomas presumed to be a secondary homonym of Cricetus obscurus Milne Edwards, for which Cricetus furonculus: combination. Thomas, 1908a: 107. Name Cricetulus griseus obscurus: Lesson, 1842: 119. Name combination and new rank for obscurus . combination and incorrect subsequent spelling of Cricetulus griseus fumatus M[us] Cricetus Furunculus: J. F. Gmelin, 1792: 245. Name combination. Trouessart, 1904: 395. Name Cricetus Furunculus: Brandt, 1859a: 208. Name Chun, Kirin [Jilin] Province”, China. combination. Cricetulus furunculus: Formozov, 1929: 40. Name Cricetulus griseus A. Milne Edwards, 1867: 376. Type combination. furunculus Pallas. locality: “Chu Chia Tai [Cihu Chia Tai], near Chang Thomas, 1909: 503. Type locality was not reported in the description but in Formozov, 1929: 40. Cr[icetulus] griseus fumotus: the accompanying set of plates (Milne Edwards & Incorrect subsequent spelling of fumatus Thomas. Milne Edwards 1868–1874); the figured C. griseus Cr[icetulus] furunculus obscurus: Formozov, 1929: 47. was from the “environs de Pékin” (Plate 12, Figure Name combination. 1). In his 1871 paper, Milne Edwards stated on p. Cricetulus manchuricus Mori, 1930: 419. Type locality: 133 that the species was very common around “Harbin, North Manchuria”, now Heilongjiang Beijing (“très-commune dans les champs aux Province, China. environs de Pékin”) and Rode (1945: 20) is explicit Cricetulus furunculus : Kuznetsov, 1932: 97. Name that the type was from “Pékin”. Although combination. Chaworth-Musters (1933: 222) accepted “the [ Cricetulus] (Cricetulus) barabensis: Argyropulo, 1933b: neighbourhood of Pekin” as the type locality of 246. First use of the current name combination. griseus , Ellerman & Morrison-Scott (1951: 624) relied [ Cricetulus ( Cricetulus) barabensis ] obscurus : Argyropulo, on a manuscript note by Oldfield Thomas that a 1933b: 246. Name combination and new rank. “Specimen marked as type in Paris Museum [was] SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 45. [Cricetulus (Cricetulus) barabensis] griseus: Argyropulo, C[ricetulus] b[arabensis] ferruguneus Iskhakova, 1974: 232. 1933b: 246. Name combination and new rank. Incorrect subsequent spelling of ferrugineus Cricetulus barabensis fumatus: Chaworth-Musters, 1933: Argyropulo 233. Name combination. Cricetulus barabensis xinganensis Wang, 1980: 316. Type Cricetulus barabensis manchuricus: Chaworth-Musters, locality: “Moli Dawa Banner, Heilongjiang”, China 1933: 233. Name combination. (Molidawa, Heilongjiang Province, China; Corbet C[ricetulus] f[urunculus] barabensis: Vinogradov, 1933: 45. 1984: 14). Name combination. [Cricetulus (cf.) pseudogriseus] manchuticus: Malyguin C[ricetulus] griceus: Mori, 1939: 23. Incorrect subsequent [typographical error for Malygin], Startzev & Zima, spelling of griseus Milne Edwards. 1992: 37. Incorrect subsequent spelling of Cricetulus barabensis ferrugineus Argyropulo, in: manchuricus Thomas. Vinogradov & Argyr[opulo], 1941: 170. Type Cricetulus barabensis tuvinicus Iskhakova, Lebedev & locality: “южные районы Уссурийской обл.”, i.e. Lissovsky, in Lebedev & Lisovsky [sic] 2008: 371. southern Ussuri region, Russian Federation. Type locality: “в окрестностях с. Саглы, Baranova & Gromov (2003: 46) restricted the type Овюрского р-на, Тувинской АССР (в настоящее locality by designating the lectotype (ZIN S. 18889) время Республика Тыва” [vicinity of village Sagly, from “дер. Сергиевка, Гродековский р-н, Ovyrskiy Rayon, Tyva Autonomous Soviet Socialist Владивостокский окр. (Партизанский р-н, Republic (currently Republic of Tyva)], Russian Приморский кр.)” [village Sergievka, Federation. Grodekovskiy Rayon, Vladivsotokskiy Okrug (Partizanskiy Rajon, Primorskiy Krai)]. Etymology. Type locality of Cricetulus barabensis is in Lectotypification, however, does not contain an Baraba steppe or Baraba Lowland (Барабинская express statement of deliberate designation as низменность) in western Siberia (Russia). The species’ requested by the amended Article 74.7.3 of the Code epithet therefore alludes on the geographic origin of the (Declaration 44; ICZN 2003) and is therefore not type. valid (Kryštufek & Shenbrot 2023). [Cricetulus (Cricetulus) barabensis] furuuculus: Kuznetzov, Nomenclature. The year of publication for obscurus 1944: 321. Incorrect subsequent spelling of and longicaudatus, which is nearly uniformly reported as furunculus Pallas. 1867 (Trouessart 1897, Ellerman 1941, Ellerman & Cricetus (sic) pseudogriseus Iskhakova, 1974: 231. Type Morrison-Scott 1951, Pavlinov & Rossolimo 1987, Luo locality: “southern Transbaikal region”, et al. 2000, Wang 2003, Musser & Carleton 2005, Jiang subsequently restricted to “на юге Бурятской et al. 2015, etc.), with reference to “Rech. Mamm.” АССР, Кяхтинском р-не, в окресностях станции [Recherches pour servir à l’histoire naturelle des Наушки”, i. e. the vicinity of Naushki station, Mammifères], is obviously erroneous because Kyakhtinskiy rajon, southern Republic of Buryatiya, “Recherches” by Henry and Alphonse Milne Edwards Russian Federation. were released between 1868 and 1874 (Anonymous C[ricetulus] b[arabensis] tuvinicus Iskhakova, 1974: 232. 1875, Allen 1940: 761) and therefore postdate 1867. Not ‘Orlov & Iskhakova’ (Gromov & Baranova Chaworth-Musters (1933: 223) quoted for obscurus the 1981: 157). The name tuvinicus was proposed for year 1868, while some authors (Allen 1940: 761, Ross hamsters occupying Tuva and northwestern 1982: 248, Orlov & Malygin 1988: 304) gave the entire Mongolia. Nomen nudum (cf. Corbet 1984: 14, range of dates (1868–1874). As stipulated by the Code Gromov & Erbajeva 1995: 319). (Art. 21.6; ICZN 1999), in such cases the work should Cricetulus pseudogriceus: Orlov, Radzhabli, Malygin, be dated from the final day of the range (i. e. 1874), as Khotolkhu, Koval'skaya, Bulatova, & Baskevich, was done by Rode (1945: 30). However, since the work 1978: 157. Incorrect subsequent spelling of was published on different days (cf. Günther 1871: 2), pseudogriseus Iskhakova. the date of the Chapter “Études pour servir a l’histoire de la faune mammologique de la Chine” with Cricetulus obscurus and longicaudatus is to be determined. 46 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Zoological Record registered these names in 1871 Major evidence for tripartite taxonomy was therefore (Günther 1871: 2) and the “Études [...]” (Milne provided by karyology (Corbet 1978, Ross 1992). Edwards 1871: 284) date the 7th volume of the Various authors, however, stressed the absence of “Nouvelles Archives du Muséum” as released in 1871. cytological differences between the 3 cytotypes besides David, in his 1871 report addressed to the Muséum the count of chromosomes. These cytotypes share d’histoire naturelle in Paris, lists longicaudatus and obscurus identical number of chromosomal arms (NF = 38) and (David 1871: 93), hence the two names were available differential staining allowed for a full homologation of no later than 1871. The exposed evidence shows these arms. The differences in the diploid counts can be beyond doubt that longicaudatus and obscurus were explained by 1–2 Robertsonian fusions. Furthermore, published in 1871 (cf. Corbet & Hill 1992: 392). nucleolus organizer regions (NOR) were found in 6 identical chromosomal pairs in all 3 cytotypes. These Taxonomy. The name Mus barabensis Pallas was homologies questioned the utility of chromosomal overlooked throughout the 19th century until being evidence in species delimitation (Král et al. 1984). simultaneously restored by Chaworth-Musters (1933) Furthermore, a recent phylogenetic reconstruction and Argyropulo (1933b, c). Prior to this, the striped based on mtDNA cytb gene questioned the monophyly lesser hamster was referred to as griseus (Thomas 1888, of barabensis as defined by Orlov & Iskhakova (1975). 1908a, 1909, Trouessart 1904, Kashchenko 1910, Allen Viable F1 hybrid offsprings were produced in breeding 1925, Howell 1929, Kuroda 1939) or furunculus (Gmelin trials between all 3 cytotypes (Poplavskaya et al. 2012) 1792, Lesson 1827, 1842, Kashchenko 1910, Formozov despite some sporadic disorders in meiotic prophase I 1929, Kuznetsov 1932, Beljaev 1933, Vinogradov in hybrid hamsters (Matveevsky et al. 2014). In nature, 1933). Taxonomic scope was fairly stable with a single the intermediate karyotype (2n = 21) was found only in obvious deviation, specifically the inclusion into Central Mongolia in the contact zone between the 20 barabensis of C. dichrootis Satunin, 1902 (now a synonym and 24 cytotypes (Poplavskaya et al. 2012). There is also of C. longicaudatus) and C. kozlovi Satunin, 1902 (now in little phenetic alteration among the cytotypes of striped Nothocricetulus migratorius) (Allen 1940). lesser hamsters (Ross 1992, Lebedev & Lisovsky 2008), though Orlov & Iskhakova (1975) report on differences In 1960, Matthey (1960) reported differences in the in shape of baculum and sperm head. Application of diploid number between barabensis (2n=20) and obscurus molecular clock on mtDNA sequences estimated (2n=22), which he considered to be an intraspecific TMRCA at 0.16 Mya (CI = 0.01–0.34 Mya), which is phenomenon. Regardless of this, Vorontsov (1960) much less than is the TMRCA for C. longicaudatus (0.33 elevated the two cytotypes to species rank, hence Mya, CI = 0.02–0.68 Mya) (Lebedev et al. 2018a). barabensis and obscurus started to be treated as species in Fossils attributed to C. barabensis are from the latest their own right (Zimmermann 1964, Flint 1966b). In Early Pleistocene (Erbajeva et al. 2021) and thus 1970s, Iskhakova (1974) described an additional predate TMRCA. cytotype (2n = 24) of the striped lesser hamster and named it as a new species pseudogriseus (nomen nudum; Relying on the above evidence, particularly on Král et properly named in Orlov & Iskhakova 1975). The al. (1984), many authors continued classifying the majority of authors writing on striped lesser hamsters striped lesser hamster as a single polytypic species C. during 1980s (Sokolov & Orlov 1980, Gromov & barabensis (Corbet 1978, Corbet & Hill 1980, Baranova 1981, Vinogradov & Gromov 1984, Pavlinov Vinogradov & Gromov 1984, Musser & Carleton 1993, & Rossolimo 1987) and beyond (Malygin et al. 1992, 2005, Pavlinov et al. 1995, Zhang et al. 1997, Luo et al. Ross 1992, Gromov & Erbajeva 1995, Panteleyev 1998, 2000, Pavlinov 2003, 2006, Smith & Hoffmann 2008, Wang 2003) accepted a tripartite taxonomy. Honacki et Lebedev 2012, Korablyov et al. 2013, Matveevsky et al. al. (1982) and Corbet & Hill (1986) even recognized 4 2014, Jiang et al. 2015, 2017, Pardiñas et al. 2017, species of striped lesser hamsters (barabensis, griseus, Lissovsky et al. 2019). The authors who opposed this pseudogriseus, and obscurus) view exposed restricted gene flow between the 20 and 24 cytotypes (e.g. Vakurin et al. 2014, Poplavskaya et al. 2017b). In biomedical research, the striped lesser SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 47. hamster is still referred to as the Chinese (grey) hamster other large Siberian Rivers (Ob, Yenisei, Angara, and Cricetulus griseus (Chang et al. 1987, Field & Sibold 1999, Lena), Lake Baikal, and the upper and middle flow of Bihun & Bauck 2005, Feeney 2012, Becvar et al. 2024). the Amur River. The southern border is defined by the upper reaches of the Irtysh, the Altai, Mongol Altai, Cricetulus barabensis is a sister species to C. sokolovi; Gobi Altai, and Gobi Desert. In eastern Mongolia, the divergence time is estimated at 0.33 Mya (CI = 0.05– range border turns sharply south and west towards the 0.69 Mya; Lebedev et al. 2018a). eastern Qilian Mts. From there, the range border turns south-east, encompassing the Ordos Loop and the Distribution. The range covers 2,736,000 km2 in plains between the lower Huang He and the Yangtze eastern Asia, specifically in Russia (south-eastern parts Rivers. of West Siberian Plain, southern Siberia, and Primorye), northern and central Mongolia, north-eastern China The striped lesser hamster occupies steppe and forest-and marginally north-eastern Kazakhstan (provinces of steppe zones and penetrates marginally into East Kazakhstan and Pavlodar) and North Korea semideserts. It is inhabitant of structurally simple (provinces of North Hamgyong and North Pyong-An) grassland habitats (usually with Caragana shrubs), (Figure 31). The western border is approximately 150 farmland, scrubs and hedgerows, and was occasionally km to the west of the middle reaches of the Irtysh, and captured in light woodland. Prefers sandy substrate; in the eastern border is set by the Ussuri and Yalu Rivers, semideserts frequents fixed sands with shrubs and also and the shores of the eastern Korean Bay, Bohai Sea, settles on saline substrate. Synanthrope in many parts and the Yellow Sea as far south as the estuary of the of its range. Elevational range is from sea level up to Yangtze River. The northern border is tentatively set by 3,200 m a. s. l.; the majority of records are from low the middle reaches of the Irtysh, the upper reaches of elevations (mean = 780 m). Figure 31: Distributional range of the striped lesser hamster Cricetulus barabensis. 48 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 32: Striped lesser hamsters Cricetulus barabensis from Mongolia. a – C. b. barabensis; b – C. b. pseudogriseus. Note a bold stripe on the forehead of individual in inset (a). Photo courtesy of Annegret Stubbe Characteristics. Small and short-tailed hamsters (tail with whitish hairs; hairs on the outer side are black; the accounts for 24–31% of head and body length) with top of the ear is bordered white. There is a white post- moderately large eyes, pointed snout, and long circular auricular tuft. Short hairs covering paws, wrists and ears (Figure 32). Dimensions: body mass = 21–41 g, ankles are white to base. The soles are densely furred length of head and body = 90–117 mm, length of tail = posterior to pads with spares hair between them (Figure 20–30 mm, length of hind foot = 14–17.5 mm, ear 33a). Tail is thick at the base and gradually tapers length = 13–17 mm, condylobasal length = 21.2–27.5 towards its tip; it is densely covered by spinous hairs, mm, zygomatic width = 12.2 –16.2 mm, length of which form a feeble pencil; additional longer whitish maxillary tooth-row = 3.5–4.4 mm. Males are on hairs protrude from the tail’s base (Figure 29a). average heavier (mean body mas ± SD = 37.7 ± 1.38 g) than females (33.4 ± 1.30 g; data from captive C. b. Fur is soft and dense, 7.5–11 mm long on the mid-back griseus; Chernova et al. 2022a). Vibrissae are up to 22– with sparse longer hairs protruding for additional 1–1.5 27 mm long, either white or blackish-brown. The inner mm. Hairs on the dorsal side are typically tricoloured, side of pinnae is pigmented grey and is sparsely covered with slate base, buffy subterminal band and black tip. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 49. Figure 33: Left palm (top row) and sole (bottom row) in hamsters from the subtribe Cricetina: a – Cricetulus barabensis (China); b – Nothocricetulus migratorius (bottom – Afghanistan; top – Izmir, Turkey); c – Allocricetulus eversmanni (Tatarstan, Russia); d – Cricetus cricetus (Hungary). Digits are shown in Roman numerals (thumb = I) and interdigital pads are shown in Arabic numbers; pads: mm / MM – medial metacarpal / metatarsal pad; ml / ML – lateral metacarpal / metatarsal pad. Scale bars = 5 mm. Colouration of the dorsal surface, from the muzzle to the root of the tail, the cheeks, upper arms and thighs, on the ventral side expand posteriorly covering ~½ of is highly variable, ranging from ochraceous buff to the surface. At the base is a prominent protuberance reddish-brown and to dull grey (see under subspecies). covered by spines which are 2–3-times the size of The mid-dorsal stripe is usually present but varies spines on the distal glans. The central papilla bifurcates individually and among subspecies, being either black and is wider than lateral papillae (Tokuda 1941); there and bold, thin and interrupted, dissolved or even are also 2 ventral papillae, while the dorsal papilla is obscured entirely (Figures 36 & 37). It extends from the absent (Vorontsov 1982). Baculum is slender and crown of the head to tail base, but this also varies; the usually with expanded base (17d). Trident is of stripe is 1.5–4 mm wide. Underside is grey; hair bases approximately same length as the proximal shaft; lateral are slate and tips are either grey or white. Dark slate of denticles are gently bent and are of same size as the hair bases clouds the underside dark grey. Demarcation straight central denticle (Argyropulo 1933c, Ross 1992). line on the flanks is distinct and almost straight. Tail is The skull has comparatively short rostrum; nasals reach usually sharply bicolour, black or dull brown above, further posteriorly than in C. longicaudatus, and the white below. Juveniles are usually duller and greyer than posterior edge of palate is closer to M3 than in C. adults; they already have a mid-dorsal line. sokolovi. Zygomatic arches tend to be more expanded than in C. longicaudatus; zygomatic width accounts for Glans penis is of cylindrical shape with truncate distal 50.0–59.5% of condylobasal length (mean = 54.9%) end; it is 5.1 mm long, 2.9 mm wide and 2.6 mm deep. (Figure 34). Dentition shows no peculiarities (Figure Distally, the glans is densely covered with spines which 35). 50 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 34: Skull and mandible in lesser hamsters Cricetulus. Top to bottom: C. barabensis (Xing’an, Shaanxi, China), C. sokolovi (Orog Nuur, Mongolia), and C. longicaudatus (Mongolia). SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 51. Figure 35: Grinding pattern of upper (a, b, c) and lower (a’, b’, c’) molars in lesser hamsters of different age: Cricetulus barabensis (a, b) and C. sokolovi (c). Acronyms: if2 – the 2nd internal fold; pf2 – the 2nd primary fold. Origin of vouchers: a – Buir nuur, Mongolia; b – Ononsky Rayon, Russian Federation; c – Orog Nuur, Mongolia. Karyotype is polytypic with 3 allopatric cytotypes among populations (Ross 1992). Craniometric study by differing in diploid numbers. These cytotypes are Lebedev & Lisovsky (2008) demonstrated a north-to-frequently labelled by taxonomic names, which we south trend in size, with smaller hamsters in the north parenthesize: 2n = 20 (barabensis cytotype), 2n = 22 (Russia and western Mongolia), and larger hamsters in (griseus cytotype), and 2n = 24 (pseudogriseus cytotype). the south (eastern Mongolia and China). The species is Fundamental number is the same across all cytotypes neatly structured into 3 allopatric chromosomal races (NF = 38) and heterochromosomes are invariably bi- (see below and Characteristics above). Phylogeographic armed (submetacentric or metacentric), either medium- structuring similarly shows a clear pattern which is sized (the X chromosome) or rather small (the Y largely consistent with the distribution of cytotypes. A chromosome); pseudogriseus was originally reported to phylogenetic tree based on mtDNA cytb gene yielded 2 have acrocentric Y chromosome (Orlov & Iskhakova clusters, one containing the 2n = 20 cytotype, and 1975). The autosomal complement consists of 8 pairs another with 2 monophyletic lineages, comprising the of metacentric and 1 pair of acrocentric chromosomes 2n = 22 and 2n = 24 cytotypes, respectively in the barabensis cytotype, 7 pairs of metacentric and 3 (Poplavskaya et al. 2018a). pairs of acrocentric chromosomes in the griseus cytotype, and 6 pairs of metacentric and 5 pairs of Variation as outlined above can be reasonably well acrocentric chromosomes in the pseudogriseus cytotype accommodated with traditional trinomial taxonomy. So (Orlov et al. 1978, Král et al. 1984). far, the majority of authors have recognized 4 subspecies (Argyropulo 1933b, c, Ellerman 1941, Variation and subspecies. Individual and Iskhakova 1974) or 5 subspecies (Chaworth-Musters geographical variation is most obvious in colouration, 1933, Ellerman & Morrison-Scott 1951, Corbet 1978). and Vorontsov (1982) considered this trait dimorphic. Four subspecies have been recognized in the former He classified hamsters either as reddish or greyish. Soviet Union (Vinogradov & Argyropulo 1941, Though the reality is more complex, this simplification Kuznetzov 1944, Gromov et al. 1963, Kuznetsov 1965, exposes the latitudinal trend along the northern edge of Gromov & Erbajeva 1995) however Chinese authors species’ distribution. All hamsters are grey in the admitted higher number of subspecies for China: 5 western part of their range in Siberia, contrary to 95.5% subspecies (Zhang et al. 1997, Luo et al. 2000) or 6 of reddish individuals at the eastern edge in the Ussuri subspecies (Wang 1980); Wang (2003) listed 8 Region. Morphometric studies stressed great similarity subspecies which he grouped into 3 species. 52 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 36: Skins of striped lesser hamster Cricetulus barabensis from the subspecies group barabensis: a – Kyakhtinskiy Rayon, Buryatia, Russia; b – Khovsgol nuur, Mongolia; c – Sretenskiy District, Zabaykalsky Krai, Russian Federation; d – Borzinskiy Rayon, Russian Federation; e – 200 km west of Heihe, Nei Mongol-Heilongjiang border, China; f – Xing’an, Shaanxi, China. Subspecies identities: C. b. barabensis (a, b), C. b. fumatus (c–f). Subsequently, we recognize 5 subspecies in 2 groups. Cricetulus barabensis barabensis Sampling for karyological and molecular phylogenetic (Pallas, 1773) analyses was dense in Russia and Mongolia, but sparse in China. The provinces of Heilongjiang, Jilin, and the eastern parts of Nei Mongol with type localities for 3 Synonyms: Mus furunculus Pallas, 1779 (unnecessary nominal taxa ( renaming of barabensis Pallas); Cricetulus barabensis fumatus, manchuricus, xingangensis ) remain tuvinicus Iskhakova, 1974 (nomen nudum); Cricetulus particularly under-sampled, which poses some barabensis tuvinicus Lebedev & Lissovsky, 2008. uncertainty in the proposed subspecific taxonomy. Subspecies group barabensis Taxonomy. Phylogenetic reconstruction by Poplavskaya et al. (2018a) clustered tuvinicus with the nominotypical barabensis and we classify these names as The group contains 3 subspecies sharing the diploid synonymous. When described (Lebedev & Lisovsky number 2n = 20. Spinal stripe is black, heavy and 2008), tuvinicus was defined by colouration, but was not distinct, frequently bold, carried forward on the crown compared with the nominotypical barabensis. of the head where typically expanded into a patch (Figures 32a, 36a, c, e & f). In comparison with the Distribution. The western and north-central part of griseus group, the proximal baculum is wider across its species’ range in Russia, Kazakhstan, and Mongolia, as base, but has a narrower stalk and the transition far east as the line: Hujirt and Kharkor (Ovorkhangai between the two is rather abrupt; the medial denticle of Province, Mongolia) – confluence of the Uur Gol and distal baculum is narrower. Sperm head (without Uilgan Gol Rivers (Hovsgol Province, Mongolia) – acrosome) is shorter and wider; length-to-width ratio = Zarubino and the Chikoi River (Republic Buryatia, 3.1 (Orlov & Iskhakova 1975). Russia) – Sokhondo Nature Reserve (Zabaikalsky Krai, SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 53. Russia) – central Lake Baikal and the upper Lena River Russia (Poplavskaya et al. 2018a) and most probably (Russia; Poplavskaya et al. 2018a). encompasses also north-eastern Heilongjiang (China). Borders in Heilongjiang and Jilin are not resolved. A Characteristics. Characterized by the nucleotide distributional range, very similar to the one defined sequence of cytb (Poplavskaya et al. 2018a). A small here, was in the past proposed for fumatus by various subspecies with dark dorsal pelage and distinct black authors (Vinogradov & Argyropulo 1941, Kuznetzov stripe (Figures 32a & 36a, b); individuals with reddish 1944, Kuznetsov 1965, Gromov & Erbajeva 1995). shades are exceptional. The eastern populations are paler and greyer than the western ones. Characteristics. Characterized by the nucleotide sequence of cytb (Poplavskaya et al. 2018a). Colouration Cricetulus barabensis fumatus is variable but rusty tints usually dominate (Figure 36c– Thomas, 1909 f); in Russia, Vorontsov (1982) classified 82–83% of hamsters as being reddish; the remaining are greyish- brown. Russian authors (e.g. Gromov et al. 1963) Synonyms: Cricetulus manchuricus Mori, 1930; Cricetulus frequently claim that fumatus is intermediate in barabensis xinganensis Wang, 1980. colouration between barabensis proper and ferrugineus. Black dorsal line is usually heavy and distinct, carried Etymology. Latin ‘fumus’ (fumare) translates as forward on the crown of the head. Ventral side is grey, ‘smoke’ (smoked); the subspecific epithet fumatus though hairs are frequently tipped white. therefore means ‘smoked’ in allusion to greyish tint of dorsal pelage. Cricetulus barabensis ferrugineus Taxonomy. Argyropulo, 1941 Luo et al. (2000) and Wang (2003) classified fumatus, manchuricus, and xinganensis as The Latin ‘ferrugo’ (ferruginis) translates Etymology. subspecies in their own right with ranges in south- as ‘iron rust’, hence the epithet ferrugineus means ‘rusty- eastern Heilongjiang, Jilin, and Nei Mongol ( fumatus ), coloured’ in allusion to the fur colouration. eastern Heilongjiang ( manchuricus ), northern Heilongjiang and Nei Mongol (xinganensis). Any of these Taxonomy. Russian authors usually restrict ferrugineus subspecies has been karyotyped or screened for to the Ussuri region (Vinogradov & Argyropulo 1941, molecular makeup, hence their taxonomic assessment Kuznetzov 1944, Gromov et al. 1963, Kuznetsov 1965, relies entirely on morphology. The results of different Iskhakova 1974, Orlov & Iskhakova 1975), which authors are unsurprisingly contradictory. For example, accords the molecular results (Poplavskaya et al. 2018a). Orlov & Iskhakova (1975) classified striped lesser Lebedev & Lisovsky (2008) mapped ferrugineus for hamsters from Heilongjiang and Jilin as members of the Heilongjiang and along the entire Amur River from its barabensis group, while Lebedev & Lisovsky (2008) source (here classified as fumatus). Chinese authors (Luo pooled them into the griseus group. Similar discrepancies et al. 2000, Wang 1980) synonymized ferrugineus with C. are to be found elsewhere as well; e. g. H. K. Won (1968) b. manchuricus. quote for North Korea a subspecies fumatus (the barabensis group), while Jo et al. (2018) state it is griseus Distribution. Known from the vicinity of Lake (the griseus group). Khanka, south-western Ussuri region (Primorye Region, Russia; Poplavskaya et al. 2018a). Lebedev & Distribution is in several fragments. The north- Lisovsky (2008) reported ferrugineus for central western fragment in Zabaikalsky Krai (Russia) is Heilongjiang and set the western border on the tentatively delimited by the line Shaksha – Lake Songhua River, the tributary of the Amur. Probably Balzinskoe – Maly Bator – Nerchinsk – Mankovo – occurs also in Korea (Gromov & Erbajeva 1995). Kuznetsovo – Gazimursky Zavod – Zhidka (Poplavskaya et al. 2018a). The north-eastern fragment Characteristics. Characterized by the nucleotide stretches along the mid-flow of the Amur River in the sequences of cytb (Poplavskaya et al. 2018a) and Amur Region and Jewish Autonomous Region in 54 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 37: Skins of striped lesser hamster Cricetulus barabensis from the subspecies group griseus: a–d Buir nuur, Mongolia; e, f – 200 km north-east of Chengde, Hebei. Subspecies identities: C. b. pseudogriseus (a–d), C. b. griseus (e, f). colouration. Argyropulo diagnosed ferrugineus as dull Cricetulus barabensis griseus coloured, with ample reddish tint (Vorontsov & A. Milne Edwards, 1867 Argyropulo 1941); this subspecies is gloomier than fumatus (Orlov & Iskhakova 1975). According to Vorontsov (1982), 95.5% of hamsters of this subspecies Synonyms: Cricetus obscurus A. Milne Edwards, 1871; are reddish. The stripe is clear. Cricetus mongolicus Thomas, 1888 (unnecessary renaming of obscurus). Subspecies groups griseus Etymology. In Latin, ‘griseus’ (griseum) means ‘grey’, which is allusion on pelage colouration of these The group contains 2 subspecies with diploid number hamsters. of chromosomes 2n > 20. Spinal stripe is narrower and less distinct than in the barabensis group, frequently Taxonomy. Since the 19th century, griseus has been in truncated at both ends, and therefore not always use as a species epithet for all striped lesser hamsters reaching the crown of the head. The stripe is and still is used this way in biomedical research. occasionally interrupted, obscured or even obliterated Traditionally, C. griseus was split into 2 subspecies, the (Figure 37e, f). In comparison with the barabensis group, nominotypical and obscurus (Allen 1925, and subsequent the stalk of baculum is narrower across its base, but has authors). In Allen’s view, obscurus is “[a]t best […] a a chunkier stalk and the transition between the two is poorly marked subspecies”. Corbet (1978) smooth; the medial denticle of the distal baculum is synonymized obscurus with C. b. griseus, which is followed heavier. Sperm head (without acrosome) is longer and here. Wang (2003), on the other hand, classified obscurus narrower; length-to-width ratio is 5.8 (Orlov & as a subspecies of C. barabensis, and elevated C. griseus to Iskhakova 1975). In the cytb phylogenetic tree, the a species in its own right. Within C. griseus, Wang (l. c.) griseus group emerged as a monophyletic lineage recognized 2 subspecies, the nominal with a range in (Poplavskaya et al. 2018a). Liaoning, Nei Mongol, Hebei, Beijing, Tianjin, Shandong, Henan, and Shanxi, and an undescribed SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 55. “Anhui form” from Anhui and northern Jiangsu; he Rossolimo ( l. c.) and quoted a subsequent paper by reported obscurus for eastern Gansu, central Nei Orlov & Iskhakova (1975) as the first valid naming of Mongol, Ningxia, norther Shaanxi, and Shanxi. pseudogriseus. We concur with Lebedev (2012) that naming of pseudogriseus in Iskhakova (1974) is valid. The names griseus and obscurus, as applied in the past to striped hamsters from Mongolia, represent the current Lebedev & Lisovsky (2008) stressed that pseudogriseus is pseudogriseus and sokolovi, respectively (Allen 1925, 1940, likely predated by Mus furunculus Pallas, 1779, which Formozov 1929, Vinogradov & Argyropulo 1941, would, in their view, necessitate designation of the Bannikov 1954, Zimmermann 1964, Sokolov & Orlov neotype for furunculus in order to stabilize nomenclature. 1980). Furthermore, the type locality restricted by the neotype should be in the historic Dauriya, which is one of 3 Distribution. Endemic to Chinese provinces of Hebei, localities quoted by Pallas for furunculus. Messerschmidt Beijing, Shanxi, Shandong, Jiangsu, Anhui, Henan, indeed reported furunculus (as Furrunculus myodes) from Hubei, central Nei Mongol, Ningxia, central Gansu, “Dalai Nor” [Lake Hulun, Nei Mongol, China] (Pallas Shaanxi, and Tianjin. The northern border is tentatively 1779: 273, footnote) or “Dalaï Lacum Dauuriæ”, as on the eastern Qilian Mts., the Ordos loop, and the line Pallas (l. c.) formulated it. As we stressed above (see Xilingol – Yellow Sea. Synonymy under C. barabensis), furunculus is a renaming of barabensis, and not a name for a new species (see also Characteristics. Characterized by nucleotide Chaworth-Musters 1933, and Allen 1940), hence no sequences of cytb (Poplavskaya et al. 2018a), the typification is needed for defining its scope. Even if this karyotype (2n = 22), and colouration. Dorsal pelage is would not be the case, the type locality has already been generally paler and lacks reddish tinge which is typical restricted, e. g. the Baraba Steppe (Vinogradov 1933: 45) of the barabensis group. The mid-dorsal stripe is or “Altaisky Krai, Barnaul” (Pavlinov & Rossolimo commonly not so well defined or fades entirely; on the 1987: 167). Such a restriction would satisfy the crown of the head, the stripe is hardly noticeable requirements of the Code (ICZN 1999), considering (Figure 37e, f). Back is ochraceous-buff to pale-brown that among the 3 localities quoted by Pallas (1779: 273) with sandy tint; ventral hairs have slate bases and white there is also “arenoſa regione Barabenſium camporum, tips. The skull of griseus has on average wider and deeper inter Barnaul & Kaſmala rivos, verfus Obum”, i. e. rostrum and narrower M1 than pseudogriseus (Lebedev & “between the Kasmala and Barnaul [Barnaulka] Rivers” Lisovsky 2008). (Chaworth-Musters l. c.). Cricetulus barabensis pseudogriseus Since 2000, pseudogriseus is occasionally still classified as Ishakova, 1974 a species in its own right (Wang 2003, Vakurin et al. 2014, Bazhenov 2022). Etymology. The epithet pseudogriseus is composed of Distribution. Southern Buryatia and Zabaikalsky Krai ‘pseudos’ (Greek for ‘false’) and griseus which is a in Russia; provinces of Arhangay, Bulgan, Selenge, Töv, subspecific name for Chinese lesser hamsters (see Ulaanbataar, Hentiy, Dornod, and Sühbaatar in above). When the name was coined, griseus and Mongolia (possibly also Ovorhangay). In China known pseudogriseus were distinguished only karyologically. with certainty in central Nei Mongol (Poplavskaya et al. Taxonomy. Iskhakova (1974) published pseudogriseus in into the list of Chinese mammals, while Wang (2003) 2018a). Luo et al. (2000) did not include pseudogriseus a conference proceeding, while a detailed description reported it for north-eastern Nei Mongol. was still in press (Orlov & Iskhakova 1975). Pavlinov & Rossolimo (1987: 167) condemned the name as nomen The western and south-western borders tentatively nudum , because it allegedly lacks a description. This is follow the line Povorot (Buryatia, Russia) – Zuunburen not so, since Iskhakova listed diagnostic traits. (Selenge Province, Mongolia) – Saikhan (Bulgan Regardless of this, subsequent authors nearly Province) – Khashaat (Arhangay) – Bat Khaan Uul Mts. unanimously accepted the position of Pavlinov & 56 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. (Töv) – Xilin Gol, Nei Mongol (China) (Poplavskaya et западном берегу оз. Орoг-Нур” [Bayanhongor al. 2018a). The northern border stretches from Buryatia Province, Mongolian People's Republic, south- (Kiran) to Hentiy Province in Mongolia (Ulz Gol western shore of Lake Orog-Nur]. River), turning north to Zabaikalsky Krai where follows C[ricetulus] socolovi: Tembotova, 2015: 227. Incorrect a wavy line Kubukhai – Karaksar – Kovyli – Kozlovo subsequent spelling of sokolovi Orlov & Malygin. – Nerchinsky Zavod; further east, the range continues into Nei Mongol, but the details are not known. Etymology. The species epithet is eponym for Vladimir E. Sokolov (1928–1998), a Russian Characteristics. Characterized by the nucleotide mammalogist, Professor at the Moscow State sequences of cytb (Poplavskaya et al. 2018a), the University, Director of the Institute of Evolutionary karyotype (2n = 24), and colouration. Dorsal pelage is Animal Morphology and Ecology, member of the in general duller or with more reddish tinge then in Russian Academy of Sciences, and Vice-President of griseus (Figure 32b & 37a–d). In comparison to barabensis the Fauna and Flora International (Pavlov & Shishkin group, the mid-dorsal stripe tends to be thinner and not 1998). so well defined or fades entirely. Back shows various shades of brown, with different admixture of dull, grey, Taxonomy. Early students of Mongolian mammals reddish or ochraceous tints; ventral hairs have slate recognized Sokolov’s lesser hamster under the name bases and occasionally white tips. The skull of griseus has obscurus (Allen 1925, 1940, Howell 1929). Distributional on average narrower and shallower rostrum and wider map provided by Bannikov (1954) for C. barabensis M1 than griseus (Lebedev & Lisovsky 2008). obscurus accurately captured the geographic scope of C. sokolovi in Mongolia. Decisive information on the Cricetulus sokolovi Orlov & Malygin, taxonomic rank of Sokolov’s lesser hamster was 1988 – Sokolov’s Lesser Hamster provided by karyological research (Orlov et al. 1978) and translated into Linnaean taxonomy with a lag of the Cricetulus sokolovi Orlov & Malygin, 1988: 305. Type sokolovi entire decade (Orlov & Malygin 1988). The new name was readily accepted in the West and in Russia locality: “Баян-Хонгорский аймак МНР, на юго- Figure 38: Distributional range of the Sokolov’s lesser hamster Cricetulus sokolovi. The 2 records in Khovd require reconfirmation and are therefore interpreted by question mark. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 57. (e. g. Musser & Carleton 1993). Chinese authors were at Sühbaatar; there is also an isolate in the extreme south- first hesitant (e. g. Zhang et al. 1997, Luo et al. 2000) western Khovd (Mongolian Dzungaria), on the border and included Sokolov’s lesser hamster into the list of with Xinjiang (China), which requires confirmation. Chinese mammals in the early 2000s (Wang 2003). A Lesser hamsters, however, are scarce and localized recent phylogenetic analysis based on cytb gene there. E. g. during extensive field work performed in confirmed the status of sokolovi as an independent Khovd in 1978–2022 by Soviet (after 1998 the species (Poplavskaya et al. 2017a) and its sister position Russian)-Mongolian Complex Biological Expeditions against C. barabensis; time of divergence is estimated at which collected large samples of small mammals 0.33 Mya (CI = 0.05–0.69 Mya; Lebedev et al. 2018a). (housed in ZMMU), the only lesser hamsters were C. longicaudatus. Two occurrence points for Cricetulus s. str. Distribution. Endemic to Mongolia and adjacent are known from Khovd. One was dealt with in 1975 by central Nei Mongol in China (Figure 38). The range German-Mongolian Biological expedition, which covers an estimated 301,290 km2. In Mongolia, C. yielded 3 specimens originally identified as C. barabensis sokolovi occupies the provinces of Govi-Altay, and subsequently lost. The other occurrence involved Bayanhongor, Ömnögovi, Övörhangay, Dundgovi, and the Mongolian Expedition of the Museum of South- Figure 39: Sokolov’s lesser hamster Cricetulus sokolovi from Orog Nor. Note large scrotal testicles in inset (b) which reach dimensions 14 x 11 mm in adult males (cf. Orlov & Sokolov 1988). Photo courtesy of Klaus Rudloff 58 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 40: Skins of Sokolov’s lesser hamster Cricetulus sokolovi in dorsal (a, b), ventral (a’, b’) and lateral (b”) views: a – type of C. sokolovi (ZMMS S-110099); b – Orog Nur, Mongolia (SMG 15095). Western Biology (MSB, Albuquerque, New Mexico, Chernova et al. 2022a). Sokolov’s lesser hamster is more USA) which gained 4 specimens identified as C. sokolovi. sexually dimorphic (quotient of male-to-female body Since the Khovd population may represent either an mass = 1.20) than C. barabensis griseus (1.13). Tail is isolate of C. barabensis or C. sokolovi proper we call for furrier then in C. barabensis and hair largely conceal the reidentification of the MSB vouchers. underlying annulation (Figure 29b); terminal pencil is feeble (length < 1.5 mm). Soles are nude in summer but Contrary to C. barabensis, which is primarily a steppe- hairy during winter when hairs conceal the pads dweller, C. sokolovi is restricted to a semidesert zone. It (Sokolov & Orlov 1980). Vibrissae are long (27–20 occupies structurally simple habitats on rocky slopes, mm); fur is soft (7.5–13.5 mm) and dense, the sparse fixed sands, clay, and saline soils. Vegetation consists of longer all-white or all-black hairs protrude by 1.5–2.5 needlegrass, nitre bushes, Siberian pea-tree, almond mm. Colour varies from uniformly buff, lacking any shrubs, feather grass, and halophytes. Abundance is dash of black hairs, to light reddish or to grey with higher around springs and in oases. Elevational range is brownish shade (Figures 39 & 40). The fur surrounding 885–2,190 m (mean = 1,324 m). the eyes and ears is paler and some individuals have a white postauricular tuft. The nose, the buccal region Characteristics. Size and proportions are similar as in and the lower part of the temporal region are white. C. barabensis; tail accounts for 27–29% of head and body length. Dimensions: body mass = 17–25 g, length of The underside is either cream or whitish-grey; ventral head and body = 77–114 mm, length of tail = 18–32 hair bases are grey, but slate ( i. e. more blackish) in mm, length of hind foot = 13–18 mm, length of ear = barabensis. Demarcation line along the flanks is distinct 13.0–18.5 mm, condylobasal length of skull = 22.7– albeit not sharp; it is straight and set fairly high on the 26.0 mm, zygomatic width = 12.1–14.2 mm, length of flanks, but descends towards the hips. Mid-dorsal stripe maxillary tooth-row = 3.7–4.7 mm. Males are on is blackish brown, up to 3 mm wide, and extends from average heavier (mean body mas ± SD = 39.4 ± 2.01 g) the front region; on the posterior end it usually does not than females (32.9 ± 2.15 g; data from captivity; reach the tail base. The line is never sharp, but obscure SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 59. or even absent. Paws are white and ears are dull grey in Ourocricetulus, while it is of medium size in the with contrasting white margin. Tail is whitish subgenus Cricetulus (Orlov et al. 1978). Ourocricetulus throughout (Figure 29b) or with a narrow blackish- lacks the mid-dorsal (spinal) stripe, which is nearly brown stripe which fades towards the tip. Skull (Figure always present in Cricetulus s. str., and has decidedly 34) and dentition (Figure 35c) are as in C. barabensis with longer tail (cf. Key to species above). The two subgenera few minor average differences; C. sokolovi has (1) wider differ in the overall cranio-dental morphology (Ross alisphenoid region, (2) more caudally positioned 1992). Ourocricetulus has narrower rostrum and less posterior edge of the hard palate, (3) wider interorbital expanded zygomatica arches, broader palate, shorter region, and (4) shallower braincase (Lebedev & maxillary tooth-row, and longer diastema. The Lisovsky 2008). coronoid and the articular processes of the mandible are less robust (Figure 30). The 2nd internal fold (if2) and Karyotype (2n = 20, NF = 40) consists of 2 pairs of 2nd primary fold (pf2) of M1 are confluent in large metacentric, 3 pairs of medium metacentric, 3 Ourocricetulus (Figure 44) while they are separated by pairs of small metacentric, and 1 pair of large metacone in Cricetulus s. str. (Figure 35). subtelocentric chromosomes; the latter were also classified as sub-metacentrics (Poplavskaya et al. Cricetulus longicaudatus (A. Milne 2017a). Sex chromosomes are large (the X Edwards, 1871) – Long-tailed Lesser chromosome) and small (the Y chromosome) Hamster submetacentrics (Orlov et al. 1978, Poplavskaya et al. 2017a). The karyotype of sokolovi is highly rearranged, differing from the hypothetical ancestral condition by Cricetus (Cricetulus) longicaudatus A. Milne Edwards, 1871: at least 4 Robertsonian events and a centromeric shift 136. Not 1867 (See the account on Nomeclature (Poplavskaya et al. 2017a). under Cricetulus barabensis). Accompanying illustrations (Plate 12: Figure 2; Plate 13: Figures 3, Variation and subspecies. 3a, 3b, 3c), portraying a hamster from “Mongolie Monotypic. chinoise” (Figure 2), appeared in Milne Edwards & SUBGENUS: Ourocricetulus Milne Edwards (1868–1874). Type locality: new “Mongolie chinoise”; subsequently restricted to subgenus “the vicinity of Saratsi [Lifen] in northern Shansi [Shanxi], China” (Allen 1940: 761). Taxonomy. The new subgenus Ourocricetulus is a sister Cric[etulus] longicaudatus: A. Milne Edwards, in David subgenus to subgenus Cricetulus (with barabensis and (1871: 93). First use of the current species name sokolovi); divergence time between the lineages is combination. estimated at 1.06 Mya (CI = 0.50–1.64 Mya; Lebedev et Cricetulus phaeus griseiventris Satunin, 1902: 566. Not 1903 al. 2018a). The new subgenus is monospecific. (e. g. Ellerman & Morrison-Scott 1951: 624). Type locality: “Fluss Bis-shen-gol, Südabhang des Altain- Type species. Cricetulus longicaudatus (A. Milne nuru (Gobi-Altai)”, currently Bugat Soum, Bij Gol, Edwards, 1871). Govi-Altay Province, Mongolia. Cricetulus dichrootis Satunin, 1902: 567. Not 1903 (e.g. Etymology. From ‘oura’ (Greek for tail) and Cricetulus, Ellerman & Morrison-Scott 1951: 624). Type which is diminutive of Cricetus (i. e. the hamster). See locality: “Fluss Gorban-angyr-gol, Nan-shan” also Etymology under Cricetulus and Urocricetus. Do not [Gurban-Angyr-gol, Nanshan], Qinghai, China. mismatch Ourocricetulus with Urocricetus (tribe [Cricetus (Cricetulus)] dichrootis: Trouessart, 1904: 395. Urocricetini). Name combination. [Cricetus (Cricetulus)] phaeus griseiventer: Trouessart, 1904: Diagnosis and Comparison. The new subgenus is 395. Incorrect subsequent spelling of griseiventris well defined by mtDNA nucleotide sequences (Lebedev Satunin. et al. 2018a, Poplavskaya et al. 2018b). The X Cricetulus andersoni Thomas, 1908c: 642. Type locality: chromosome is the largest element in the complement “100 miles N.W. of Tai-Yuen-Fu. 8000’ [2,440 m]”, 60 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. i. e. 161 km north-west of Taiyuanfu, Baode County, [Cricetulus (Cricetulus) longicaudatus] griseiventris: Shanxi, China. Argyropulo, 1933b: 246. Name combination. Cricetulus andersoni nigrescens G. Allen, 1925: 2. Type [Cricetulus (Cricetulus) longicaudatus] dicrootis: Argyropulo, locality: “Province of Chili, 100 miles [161 km] 1933b: 246. Name combination and new rank. northeast of Peking, China.” [Cricetulus (Cricetulus) longicaudatus] andersoni: Argyropulo, Cricetulus kozhantscikovi Vinogradov, 1927: 36. Not 1928 1933b: 246. Name combination and new rank. (Ross 1992: 219). Type locality: “Тукеек-кем, б. [Cricetulus (Cricetulus) longicaudatus] nigrescens: Argyropulo, Усинский пограничный округ, Саяны [Tukeek- 1933b: 246. Name combination. kem, former Usonsky bordering districts, Sayan [Cricetulus (Cricetulus) longicaudatus] kozhantschikovi: Mts.]”. Amendment of the type locality to Argyropulo, 1933b: 246. Emendation of species “Туксэль-Хэм [Tuksel-Khem]” (Pavlinov & epithet which was originally misspelled Rossolimo 1987:168) is erroneous. Current name of kozhantscikovi. New rank and name combination. the site is Talovka River (Kozhantschikov 1926), the C[ricetulus] g[riseiventris] kozhantscikovi: Vinogradov, 1933: left tributary of the Yenisei River in the Shushenskiy 45. Name combination. (formerly Minussinskiy) Rayon, Russian Federation. C[ricetulus] l[ongicaudatus] kozhancikovi: Vinogradov & For detailed description of the locality see Djakonov Argyropulo, 1941:170. Incorrect subsequent (1926). The species epithet is eponym for a Russian spelling of kozhantschikovi Vinogradov. entomologist В. Д. Кожанчиков (cf. Vinogradov’s Cr[icetulus] l[ongicaudatus] kozhanscikovi: Kuznetzov, text) which was transliterated as V. D. 1944: 320. Incorrect subsequent spelling of Kozhantschikov or Kozhanchikov. The eponym kozhantschikovi Vinogradov. was also spelled differently by various authors (cf. C[ricetulus] l[ongicaudatus] kozhanchikovi: Gromov, spellings listed below) and was emended as Gureev, Novikov, Sokolov, Strelkov & Chapskij, kozhantschikovi: Argyropulo, 1933b (see below). 1963: 489. Incorrect subsequent spelling of Cricetulus griseiventris: Formozov, 1929: 48. New rank. kozhantschikovi Vinogradov. Figure 41: Distributional range of the long-tailed lesser hamster Cricetulus longicaudatus. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 61. Cricetulus longicaudatus chiumalaiensis Wang & Cheng, scope of longicaudatus, but Allen (1940) synonymized it 1973: 65. Type locality: “Chiumalai District with C. barabensis obscurus. Chaworth-Musters (1933) (Sewukou Valley), Qinghai Province”, China. suggested that dichrootis and kozlovi might be conspecific with longicaudatus and Flint (1966b) expressed a similar Etymology. The species epithet consists of two Latin conjecture for kamensis and kozlovi. Formozov (1929) words: ‘longus’ for ‘long’ and ‘caudatus’ for ‘-tailed’ and Vinogradov (1933) elevated griseiventris to a species (from ‘cauda’ for the tail), i. e. a ‘long-tailed’ in allusion in its own right. to the tail of C. longicaudatus, which is the longest in the genus. Throughout the first half of the 20th century, the length of tail relative to head and body was an important trait Taxonomy. Throughout the 20th century, the majority in the taxonomy of lesser hamsters above the species of authors accepted C. longicaudatus as a species in its level. Hence, Trouessart (1904) classified longicaudatus own right, though there were some nomenclatural into Urocricetus (as a subgenus of Cricetulus), along with inconsistencies. Therefore, andersoni, which was kamensis (now in Urocricetus) and triton (Tscherskia). proposed as a full species (Thomas 1908c) and kept as Subsequent authors continued keeping longicaudatus and such by Allen (1925) and Howell (1929), was kamensis in the same species group (Argyropulo 1933b, synonymized with longicaudatus by Argyropulo (1933b, c, Ellerman 1941) until Ellerman & Morrison-Scott c). Argyropulo (l. c.) also included dichrootis into the (1951) split the subgenus Cricetulus into two groups Figure 42: Long-tailed lesser hamsters Cricetulus longicaudatus from Mongolia. Photo courtesy of Georgy Ryurikov 62 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. based on size of bullae. The migratorius group rocky habitats in the steppe and semi-desert vegetation maintained current genera Cricetulus and Nothocricetulus zones, particularly the eroded slopes with exposed and the lama group contained the current Urocricetus. rocks and screes. It is present also on slopes covered by This view was widely accepted, albeit with some brushes and around fields, and is locally abundant. modifications; for example, Pavlinov & Rossolimo Readily enters residential buildings (Flint 1966a). (1987) classified longicaudatus and barabensis into the Elevational range is 140–5,150 m (mean = 1,770 m); the barabensis species group, as opposed to the migratorius highest records are from Qinghai (Zheng 1986). group. Description. Size and overall appearance are similar to Distribution. The range of an estimated 1,060,000 km2 C. barabensis, except for the lack of mid-dorsal stripe and is in 2 major fragments, one in Mongolia and the other longer tail in C. longicaudatus (Figure 42); tail accounts in China (Figure 41). These fragments are separated by for 28–49% of head and body length (mean = 37%). the irrigated flatland between the Gurvan Saikhan Mts. Dimensions: body mass = 25–45 g, length of head and and Mt. Hörh Uul (Ömnogovi Province, Mongolia), body = 83–126 mm, length of tail = 23–58 mm, length and Yin Mts. (Nei Mongol, China). The Mongolian of hind foot = 14.5–19.0 mm, length of ear = 12.0–21.0 fragment encompasses eastern and central Mongolia as mm, condylobasal length = 22.3–27.6 mm, zygomatic far east as the Khentii–Ömnogovi line (except for width = 11.7–15.1 mm, length of maxillary tooth-row Dudngovi), and very marginally also the adjacent Russia = 3.5–4.4 mm. The sexes are approximately of same (isolated populations in Altai Republic, Buryatia, size (cf. Luo et al. 2000: 52). Vibrissae are of comparable Krasnoyarskiy Kray, Tuva, and Zabaykalskiy Kray), length to the remaining lesser hamsters (length = 26.5– East Kazakhstan (Zaysan), and extreme northern 32.5 mm). There are 5 palmar and 6 plantar pads; palms Xinjiang (China). The fragment in China centres on the and soles are densely hairy to the pads. Fur is soft and Huang-He valley, and extends from Hebei, Beijing, long (length = 9–11 mm) with sparse longer hairs Tianjin, and Henan in the east, as far west as the Three protruding by 1.0–2.5 mm; there is no difference Rivers Source Region (Sanjiangyuan) in the periphery between the summer and winter fur. Tail is moderately of the Qinghai-Tibet Plateau and Gansu. The northern densely furred and the annulation is largely concealed; border is in central Nei Mongol and the southern-most terminal pencil is feeble (Figure 29c). Ears are hairy on records are from northern Sichuan. There are several both sides, grey to blackish-brown, and usually isolated records in north-eastern Nei Mongol and narrowly edged white. The white circumference tends western Heilongjiang. to be less extensive and contrasting than in Cricetulus s. str.; occasionally, the ear is grey throughout. Upper parts of head and body are uniform and darker in the centre of the back but without a definite dark line. Colouration varies from light buffy-grey to deep brown (Figure 43), but the majority of hamsters are drab or drab-grey with occasional darkening caused by denser black hairs (Figure 42). Ventral hairs have basal ⅔ slate- grey and white tips. Posteriorly, the flanks are often vaguely marked buffy. Delineation is distinct but only exceptionally sharp; demarcation line is set high, crossing the mystacial pad, the upper part of the humerus and femur, and the base of the tail. On the Figure 43: head, white marks are frequently present: a Extremes in fur colouration in the long-tailed lesser hamster Cricetulus longicaudatus: a – pale pelage (type of griseiventris; postauricular tuft, and a sub- or postauricular spot ZIN 10630); b – dark pelage (type of kozhantscikovi; ZIN 16909). which may extend further back. Tail is bicolour; dorsal The specimen in (b) lost some hair on the back. side is of same colour as back and the underside is white. The paws are pure white. Externally, C. The long-tailed hamster has rather narrow habitat longicaudatus resembles Nothocricetulus migratorius but has requirements (Meyer & Skholl’ 1977) and occupies SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 63. ventral hairs with slate bases (in migratorius, bases are & Erbajeva 1995) and Mongolia (the nominotypical white at least on chin, throat and chests) and usually subspecies; Bannikov 1954), and 2 subspecies in China white-margined ears which are plain grey in migratorius. (Allen 1925, 1940, Wang & Cheng 1973, Luo et al. 2000, Wang 2003). Synthesis of these views resulted in 3 Skull (Figure 34) is like in C. barabensis, but tends to be subspecies recognized in Haslauer (2017b): narrower across rostrum and zygomatic arches; kozhantschikovi, chiumalaiensis, and the nominotypical zygomatic width account for 49.6–56.0% of subspecies. Earlier global assessments listed higher condylobasal length (mean = 53.6%); in C. barabensis, numbers: 5 subspecies (Argyropulo 1933b, c, Ellerman the relative width is up to 59.5%. In comparison to & Morrison-Scott 1951) or 6 subspecies (Ellerman Cricetulus s.str., C. longicaudatus has on average broader 1941). palate, shorter maxillary tooth-row, and longer diastema (Ross 1992). Dentition is like in Cricetulus s. str.; the only Subspecific variation was so far addressed in 2 studies. exception is that 2nd primary and 2nd internal folds are Wang & Cheng (1973) split Chinese long-tailed lesser confluent (Figure 44). hamsters into 2 subspecies, the smaller nominotypical (with dichrootis and nigrescens), and the larger chiumalaiensis. This view was adopted by Chinese authors. Poplavskaya et al. (2018a) explored mitochondrial (cyt b) and craniometric variation and covered a significant part of distributional range. In their results, haplotypes from Qinghai and north-western Sichuan hold basal position in the phylogenetic tree but without forming a monophyletic lineage. A sample from Kham (western Sichuan) was also the most divergent in a phenogram derived from craniometric variation. While these results expose the north-eastern part of the Qinghai–Tibetan Plateau as the cradle of diversification for C. longicaudatus at ~ 150 kya (Poplavskaya et al. 2018a), they still do not facilitate a straightforward taxonomic conclusion. For the moment being, we tentatively distinguish 2 subspecies pending for further studies in Figure 44: Grinding pattern of upper (a, b) and lower (a’, b’) molars China in general and in Qinghai and adjacent regions in in the long-tailed lesser hamster Cricetulus longicaudatus from particular. Mongolia. Acronyms: if 2 – 2 nd internal fold; pf 2 – 2 nd primary fold . Karyotype: 2n = 24, NF = 40. The autosomal set Cricetulus longicaudatus consists of 3 pairs of biarmed and 7 pairs of acrocentric longicaudatus chromosomes. The X chromosome is submetacentric (A. Milne Edwards, 1871) and is the largest element in the set; the Y is metacentric or submetacentric and of slightly smaller size (Orlov et Cricetulus phaeus griseiventris Synonyms: Satunin, 1902; al. 1978). This report is consistent with Graphodatsky Cricetulus andersoni Thomas, 1908; Cricetulus (2006a), though some authors gave different values: 2n kozhantscikovi Vinogradov, 1927. = 28 (Sokolov & Orlov 1980) and NF = 40 (Král et al. 1984). The nominotypical subspecies is Taxonomy. recognized a low number of subspecies, i.e. single one central and eastern Tuva (Tyva), Greater Khingan and ( kozhantschikovi ) in Russia (Vinogradov & Argyropulo Buryatia (Poplavskaya et al. 2018b). Hamsters from 1941, Kuznetzov 1944, Vinogradov & Gromov 1956, Buryatia were classified as the nominotypical subspecies Variation and subspecies. Regional studies marginal populations are divergent, most notably from genetically fairly homogeneous, however, some of the Kuznetsov 1965, Gromov & Baranova 1981, Gromov already in the past (Borisova et al. 2001). 64 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Distribution. Its range is in Russia, Kazakhstan, Mongolia (here classified as ssp. longicaudatus). Satunin’s Mongolia, and China: Beijing, Hebei, Shanxi, and name dichrootis, described from Qinghai, predates Shaanxi. Heilongjiang, Henan, Nei Mongol, Ningxia, chiumalaiensis, hence we use it as a senior synonym. Shaanxi, Shanxi, Tianjin, and Xinjiang. The border against dichrootis has not been resolved. Distribution. The Three Rivers Source Region (Sanjiangyuan) in the periphery of the Qinghai-Tibet Characteristics. Encompasses the cytb lineage which Plateau and Sichuan; putatively present also in Gansu. is widespread in Mongolia (Poplavskaya et al. 2018b). Distribution against the nominotypical subspecies has Chinese authors (Wang & Cheng 1973, Luo et al. 2000) not been resolved. diagnosed the nominotypical subspecies by size: profile length of skull = 22.8–28.0 mm (mean = 25.7 mm), Characteristics. Comprises a bunch of highly zygomatic width = 12.4–14.5 mm (mean = 13.4 mm). divergent cytb lineages from Qinghai and Sichuan Interpopulation differences were reported for different (Poplavskaya et al. 2018b). Chinese authors diagnosed morphological traits. Ross (1992) documented size chiumalaiensis by large size: profile length of skull = 26.5– trends in certain cranial structures, specifically an east- 30.7 mm (mean = 28.3 mm), zygomatic width = 13.4– to-west decline in the length of incisive foramens and 15.5 mm (mean = 14.6 mm) (Luo et al. 2000). Large the concomitant increase in the breadth of interorbital size, however, is perhaps typical only of the population constriction and of palate. Furthermore, hamsters are in Xizang and southern Qinghai (Wang & Cheng 1973), smaller in the south (Inner Mongolia, Shanxi, and whereas hamsters from the surroundings are of smaller Shaanxi) than in the Mongolian Plateau further north size. (Ross 1992). There are also differences in fur colouration between regions (Figure 43). Hamsters are GENUS: Nothocricetulus Lebedev, darker in Beijing and along their northern border in Bannikova, Neumann, Ushakova, Russia, and paler in Mongolia, Inner Mongolia, Shanxi, Ivanova & Surov, 2018 – Grey and Shaanxi. Hamsters Cricetulus longicaudatus dichrootis Satunin, 1903 Nothocricetulus Lebedev, Bannikova, Neumann, Ushakova, Ivanova & Surov, 2018a: 342. Type Synonyms: Cricetulus longicaudatus chiumalaiensis Wang & species is Mus migratorius Pallas, 1773. Cpicetullus : Kuznetsov, 1932: 119. Incorrect subsequent Cheng, 1973. spelling of Cricetulus A. Milne-Edwards, in Etymology. The species epithet combination with migratorius. dichrootis is a combination of two words in ancient Greek, the ‘dikhrous’ (two-coloured) and ‘-otis’ (-eared) in allusion Taxonomy. Monospecific genus. to the colouration of the ear which is dark in C. Nothocricetulus migratorius longicaudus and sometimes margined white. (Pallas, 1773) – Grey Hamster Taxonomy. Luo et al. (2000) and Wang (2003) restricted chiumalaiensis to Ando and the Tanggula Mts. Mus migratorius Pallas, 1773: 703. Not 1794 (Trouessart (Xizang) and southern Qinghai, while Wang & Cheng 1897: 508). Type locality: “in graminoſis Iaı̏kum (1973) synonymized dichrootis with the nominotypical [steppes along the Yaik (now Ural) River]”; race. Furthermore, Zheng (1986) classified hamsters subsequently restricted to the “R. Ural, S.W. of from northern Sichuan, Gansu, and eastern Qinghai as Orenburg” (Thomas 1917: 452), Russian the nominotypical subspecies. This contradicts the Federation. results by Poplavskaya et al. (2018b) who showed that Mus arenarius Pallas, 1773: 704. Type locality: “in hamsters from Sichuan and Qinghai are outside the auſtralibus as Irtin [Lower Irtysh]”; Pallas (1779: scope of the widespread lineage occupying Russia and 265) provided further details: “in arenofis SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 65. Barabenfium camporum ad Irtin fl. [fields of Baraba M[us] Cricetus Acredula: J. F. Gmelin, 1792: 242. Name at Irtysh]” and “Primo inveni marem in fabuloſis combination and variant spelling of accedula Pallas. collibus Koptælye dictis”. In old Russian maps, M[us] Cricetus arenarius: J. F. Gmelin, 1792: 244. Name “Koptælye dictis” is spelled "Копьева - Copiewa", combination. while the current spelling is Kopyevo [55.93° N, M[us] Cricetus phaeus: J. F. Gmelin, 1792: 245. Name 75.02° E] in Omsk Oblast, Russian Federation. combination. Thomas (1917: 454) restricted type locality to Cricetus accedula: Pallas, 1831: 162. Name combination. “Baraba Steppes, Lower Irtish, Siberia”. Another Cricetus arenarius: Pallas, 1831: 162. Name combination. restriction to “Gratchefskoi [Grachevskiy; N50.75°, Cricetus phaeus: Pallas, 1831: 163. Name combination. E78.64°] on the Irtish River, below Semipalatinsk, Cricetus acedula: Lessone, 1842: 119. Incorrect Siberia” by Ellerman & Morrison-Scott (1951: 622) subsequent spelling of accedula Pallas. is erroneous because the site is located in the Middle Hypudaeus cinerascens Wagner, 1848: 184. Type locality: (and not Lower) Irtysh and to the south of Baraba. “Syrien” (p. 185). Trouessart (1897: 560) Still further restriction (by Pavlinov & Rossolimo synonymized cinerascens with Microtus socialis. It is 1987: 168) was to “Павлодарская обл., clear from Wagner’s description, that cinerascens is Ермаковский р-он [Pavlodar Oblast, not an arvicoline (cf. Ellerman & Morrison-Scott Yermakovskiy Rajon]” in Kazakhstan, which is on 1951: 622, Corbet 1978: 90). the left bank of the Irtysh, while Baraba is on its Cricetus isabellinus Filippi, 1865: 344. Type locality: right bank. “Teheran”, now Tehran, Iran. Glis migratorius: Erxleben, 1777: 373. Name combination Cricetus (Cricetulus) fulvus Blanford, 1875: 108. Type Glis arenarius: Erxleben, 1777: 375. Name combination locality: “Plains of Eastern Turkestan, Pámir, and Mus accedula Pallas, 1779: 257. Type locality: “a Rhymno Wakhán”; restricted to “Kashgar [Qeshqer]”, Tarim fluvio adlatum […] in colliculosa regione inter rivos Basin, southern Xinjiang, China (Thomas 1917: Irtek & Kindely”, restricted to “Казахстан, 455). Гурьевская обл., Индерский р-н” [Kazakhstan, Cricetus murinus Severtsov, 1873: 82. Based on 2 syntypes Gur’evskaya (now Atyrauskajaya) Oblast, Inderskiy from “въ степной травы вершинъ Ори” and “в Rayon] (Pavlinov & Rossolimo 1987: 168). This Сарепты”; in English version of the paper name is possibly an unintentional typographic error (Severtzoff 1876: 54), the localities are spelled “the for acredula; the later derives from Latin ‘credulus’ Summit of Ori” and “Sarepta”. Type locality was for ‘credulous’ or ‘unsuspecting’ which may be in subsequently restricted to “Sarepta” (Trouessart allusion to a fearless behaviour of the grey hamster. 1897: 508). Although Zoological Record reported If accedula is indeed due to typographic error, then the 1873 naming of murinus (Alston 1873: 18), many the name was emended to acredula by Gmelin (1792: authors quote 1876 as the year of first publication 242); see below. However, Pallas in his subsequent (e.g. Ellerman & Morrison-Scott 1951: 622, Musser publications (e.g. Pallas 1831; see below) repeatedly & Carleton 2005: 1043). Obviously, they were used accedula, while Gmelin persisted with acredula familiar with the 1876 English translation of (Gmelin 1805). Severtsov’s paper, while the Russian original from Mus phaeus Pallas, 1779: 261. Type locality: “in 1873 escaped their notice. For 1873 as the correct Aſtrachanenſi deserto, circa Zarizynum [Tsaritsyn, year see Pavlinov & Rossolimo (1987: 168). now Volgograd] præſertim”, restricted to “Lower Arvicola coerulescens Severtsov, 1879: 63. Type locality: Volga, near Sarepta [Old Sarepta]” (Thomas 1917: “Kara-kul” (p. 64), i. e. Karakul Lake, Khokhiyi 452) which matches “окрестность Сталинграда” Murgob (former Murgabskiy rayon), Tajikistan. (Kuznetzov 1944: 320), in Latin spelling “Near Cricetus arenarius: Trouessart, 1897: 507. Name Stalingrad [now Volgograd, Russian Federation]” combination (Ellerman & Morrison-Scott 1951: 622); Sarepta Cricetus accedula migratorius: Trouessart, 1897: 508. Name [since 1920 Krasnoarmeysk] is located 28 km south combination and new rank. of Tsaritsyn [later renamed Stalingrad, now Cricetus phaeus isabellinus: Trouessart, 1897: 509. Name Volgograd], Russian Federation. combination and new rank. 66 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Cricetus phaeus fulvus: Trouessart, 1897: 509. Name Satunin’s name. Hence, Thomas evidently did not combination and new rank. introduce C. m. griseiventris as a new taxonomic name. Cricetulus atticus Nehring, 1902: 3. Type locality: Ellerman & Morrison-Scott (1951: 622) commented “Pentelikon in Attica”, Greece. griseiventris Thomas as “Probably not of Satunin, Cricetulus kozlovi Satunin, 1902: 570. Not 1903 (e.g. 1902”, and synonymized it with coerulescens Ellerman & Morrison-Scott 1951: 624). Type Severtsov. Musser & Carleton (2005: 1043) retained locality: “Oase Sa-tschou” (p. 571), spelled also “Sa- combination “griseiventris Thomas (obviously not an chou” (Allen 1925: 3); currently Oasis Satschou, available name)” in the synonymy of N. migratorius; Dunhuang, Nanshan, Gansu, China. Status follows we concur that giseiventris Thomas is unavailable Lebedev & Potapova (2008). name. [Cr]icetulus phaeus: Satunin, 1902: 59. Name C[ricetulus] migratorius arenarius: Thomas, 1917: 454. combination. Name combination and new rank. [Cr]icetulus arenarius: Satunin, 1902: 59. Name C[ricetulus] migratorius fulvus: Thomas, 1917: 455. Name combination. combination and new rank. [Cricetus (Cricetulus)] atticus: Trouessart, 1904: 395. Name [Cricetulus migratorius] accedula: Thomas, 1917: 453. Name combination. combination and new rank. [Cricetus (Cricetulus)] arenarius: Trouessart, 1904: 395. Cricetulus falzfeini Matschie, 1918: 299. Type locality: Name combination. “Ascania Nova [Askania-Nova]”, “Taurien [Taurida [Cricetus (Cricetulus)] kozlovi: Trouessart, 1904: 395. Steppe, Kherson Oblast], Southern Russia [now Name combination. Ukraine]” (Ellerman & Morrison-Scott, 1951: 623). Cricetulus tauricus Satunin, 1908: 140. Nomen nudum. Cricetulus fulvus: Ognev, 1923: 89. Name combination. Publication was not seen and is quoted from Cricetulus fulvus fulvus Blanf. m. pamirensis Ognev, 1923: Pidoplitshka (1928: 426); see also Kuznetzov (1944: 89. Syntypes originated from “г. Мазарка, Памирь 247) and Pavlinov & Rossolimo (1987: 168). [Mazarka settlement, Pamir]” and “Памирский Cricetulus migratorius atticus: Miller, 1912: 593. New rank. Пост [Pamir Post; now Murgab]”. Invalid as Cricetulus arenarius bellicosus Charleman, 1915: 70. Type infrasubspecific name; validated in Vinogradov locality: “вблизи м. Степанцевъ въ Каневскомъ (1931: 4). уѣздѣ Kiевской губернiй”, i.e. Stepantsy, south of Cr[icetulus] m[igratorius] bellicosus: Ognev, 1924: 24. Name Kiev, Ukraine. Ellerman & Morrison-Scott (1951: combination. 623) spelled the author’s name as Sharleman, Cricetulus migratorius (phaeus) griseus Kashkarov, in probably transliterating the Russian variant Kashkarov et al., 1923: 215. Type locality: “гор. Шарлемань [or Шарлеманъ]. The family name Каратау, с верховьев речки Терc” [Karatau Mts., Charleman is on the cover page (see also Pavlinov from the upper flows of the Ters River], & Rossolimo 1987: 168). Zhambilskaya (Dzhambulskaya) Oblast, Cricetulus phaeus neglectus Kazakhstan. Permanently invalidated as a primary Ognev, 1916: 81. Syntypes were from “Атманай, Мелитопул у. [Atmanay, County homonym of Cricetus (Cricetulus) griseus Milne- Melitopul]” and “Бурульча, пр. Салгира, Бешко Edwards, 1867 (= Cricetulus barabensis). [Burul'cha, Salgira, Beshko]”, both on Crimea (p. Cricetulus migratorius (phaeus) caesius Kashkarov, in 84). Invalid as infrasubspecific name (aberratio); Kashkarov et al., 1923: 215. Type locality: “Аулие- validated by Pidoplitshka (1928: 426). Ата” [Aulie-Ata], now Taraz, Zhambilskaya C[ricetulus] migratorius vernula Thomas, 1917: 453. Type (Dzhambulskaya) Oblast, Kazakhstan. locality: “Khotz [now Çosandere], near Trebizond Cricetulus migratorius pulcher Ognev, 1924: 22. Type [Trabzon]”, northern Asia Minor, Turkey. locality: “бл. Лаpса, Воено-Грузинская дорога, 25 C[ricetulus] migratorius griseiventris: Thomas, 1917: 454. верст от г. Владикавказа [near Lars, Military Thomas added to griseiventris an abbreviation “Sat.” Georgian Road, 27 km from Vladikavkaz]”, (for Satunin; Northern Caucasus, Georgia. cf. Cricetulus phaeus griseiventris Satunin, 1902; now a synonym of Cricetulus longicaudatus) and Cr[icetulus] m[igratorius] bellicosus: Ognev, 1924: 24. New “from Gobi Altai”; the latter is the type locality of rank. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 67. Cricetulus migratorius cinereus Kashkarov, 1926: 23. New under pamirensis Ognev). Mazar means a mausoleum name for griseus Kashkarov. Argyropulo (1933b: in Arabic, hence the toponym possibly relates to a 247) cited type locality as “г. Пишпек, Семиречье mountain or hill with a mausoleum. Since the [city of Pishpek (now Bishkek), Semirechye]”, precise site cannot be identified, we restrict the type Kyrgyzstan; this act is not valid. The nomen novum locality to Murgab, Tajikistan. retains the same type locality as was proposed for [Cricetulus migratorius] cinerascens: Argyropulo, 1933b: 247. griseus Kashkarov, 1923. Name combination and new rank. Cricetulus migratorius zvieresombi Pidoplitshka, 1928: 421. [Cricetulus migratorius] coerulescens natio ognevi Argyropulo, Type locality: “Ростов над Доном [Rostov-on- 1933b: 427. Type locality: “окр. Самарканда Don]”, Rostov Oblast, European Russia. The name [neighbourhood of Samarkand]”, Uzbekistan. is eponym to Ukrainian entomologist Yevgeny Invalid as infrasubspecific name (natio). Validated in (Evgen) V. Zverezomb-Zubovskiy (in Russian Vinogradov & Argyropulo (1941). alphabet Зверезомб-Зубовский) (1980–1967) [Cricetulus migratorius] murinus: Argyropulo, 1933b: 247. whose name is spelled in Ukrainian as Zverozomb- Name combination and new rank. Zubovskiy (Зверозомб-Зубовский) or Zvirozomb- [Cricetulus migratorius] myosurus Argyropulo, 1933b: 247. Zubovskiy (Звірозомб-Зубовський). Both, the Nomen nudum (cf. Pavlinov & Rossolimo 1987: author’s name and the eponym, were frequently 169, Musser & Carleton 2005: 1043). Argyropulo ( l. incorrectly spelled (see below). c.) credited “Severzov [Severtsov]” as the author of Cricetulus migratorius phaeus sviridenkoi Pidoplitshka, 1928: the name but without quoting the year. We could 424. Type locality: “Кізлярського пов., м. not trace myosurus in Severtsov’s papers (1876, 1879); Арешевка, Терської Обл. [Kizlyar District, myosurus is neither mentioned in papers predating Areshevka, Terek Oblast, Daghestan]”. Explicitly Argyropulo’s 1933 naming (e.g. Trouessart 1897). proposed as infrasubspecific taxon (natio) and [Cricetulus migratorius] zvierozombi: Argyropulo, 1933b: hence invalid. 247. Incorrect subsequent spelling of zvieresombi Cricetulus migratorius phaeus: Pidoplitshka, 1928: 423. New Pidoplitshka. rank. Cricetulus koslovi: Chaworth-Musters, 1933: 222. Cricetulus migratorius neglectus Pidoplitshka, 1928: 426. Incorrect subsequent spelling of kozlovi Satunin. First appropriate use of neglectus Ognev. Type C[ricetulus] m[igratorius] ognevi Vinogradov & Argyropulo, locality restricted to “Бурульчі, доплив р. Салгира 1941: 171. Type locality: “окресности Самарканда в Криму [Burul'chi, valley of the Salgir River, [neighbourhood of Samarkand]”, Uzbekistan. First Crimea]”. use of ognevi Argyropulo as trinomen. C[ricetulus] m[igratorius] zrvieresombi: Pidoplitshka, 1928: Cr[icetulus] m[igratorius] zvierezombi: Kuznetzov, 1944: 417. Incorrect spelling of zvieresombi Pidoplitshka. 320. Incorrect subsequent spelling of zvieresombi Cricetulus migratorius falz-feini: Flerov, 1929: 395. Variant Pidoplitschka. spelling of falzfeini Matschie; felzfeini is eponym for Cr[icetulus] m[igratorius] swiridenkoi: Kuznetzov, 1944: Eduard Oleg Alexandrowitsch von Falz-Fein. 320. Incorrect subsequent spelling of sviridenkoi Cricetulus migratorius zwierezombi: Kalabuchow & Pidoplitschka. Rajewskij, 1930: 144. Incorrect subsequent spelling Cricetulus migratorius elisarjewi Afanasiev, 1953: 237. Type of zvieresombi Pidoplitshka. locality: “окресности с. Шемонаихи и разъезда Cricetulus migratorius zwerezombi: Kalabuchow & Казахстан”, i.e. the vicinity of village Shemonankha Rajewskij, 1930: 144. Incorrect subsequent spelling and railway station “Kazakhstan” (approximately 13 of zvieresombi Pidoplitshka. km north of Shemonankha, north-western foothills Cricetulus migratorius coerulescens: Vinogradov, 1931: 3. of the Altai Mts., East-Kazakhstan Region, Name combination and new rank. Kazakhstan. Corbet (1978: 91) remarked that C[ricetulus] m[igratorius] pamirensis Vinogradov, 1931: 4. elisarjewi might be nomen nudum. Afanasiev, First use of pamirensis Ognev as trinomen (listed as a however, satisfied the provisions of Articles 11 and junior synonym of coerulescens). Syntypes were from 13.1.1 of the Code (ICZN 1999), hence elisarjewi is two localities, Mazarka and Murgab (see above available name. 68 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. C[ricetulus] m[igratorius] elesarjewi: Afanasiev, 1960: 55. but Dr Pallas suspects this to be a mistake” (Gmelin Incorrect subsequent spelling of elisarjewi Afanasiev. 1792: 243). There is no current evidence on mass [Cricetulus longicaudatus] kozlovi: Flint, 1966b: 14. Name migrations in this species. combination. C[ricetulus] m[igratorius] caesius: Wang & Cheng, 1973: 62. Taxonomy. Throughout the 19th century, the grey Name combination. hamster was classified as a member of the genus C[ricetulus] kamensis kozlovi: Wang & Cheng, 1973: 64. Cricetus, but was transferred into Cricetulus in the early Name combination. 1900s (Nehring 1902, Satunin 1902, 1903) where it C[ricetulus] m[igratorius] ceorulescens: Davydov, 1988: 119. remained until recently (Ellerman 1941, Ellerman & Incorrect subsequent spelling of coerulescens Morrison-Scott 1951, Pavlinov & Rossolimo 1987, Severtsov. Musser & Carleton 2005, Haslauer 2017a). Molecular Cricetulus migratorius isbellinus: Zykov, 1991: 76. Incorrect phylogenetics unanimously retrieved paraphyly of subsequent spelling of isabellinus Filippi. Cricetulus with respect to migratorius; migratorius holds [Cricetulus migratorius] fernula: Zykov, 1991: 78. Incorrect sister position against Cricetus + Allocricetulus combined subsequent spelling of vernula Thomas. (Figure 1) (Lebedev et al. 2003, 2018a, Neumann et al. [Cricetulus migratorius] zvierezombi: Musser & Carleton, 2006, Ding et al. 2016a). The divergence time is 1993: 538. Incorrect subsequent spelling of estimated at 4.46 Mya (CI = 3.41–5.88 Mya), which zvieresombi Pidoplitshka. places the event into the Early Pliocene (Lebedev et al. Cricetulus migratorius issabellinis: Kandaurov, 2018a). Morgilevskaya & Bukhnikashvili, 1994: 132. Incorrect subsequent spelling of isabellinus Filippi. In the past, Cricetulus frequently included, in addition to Cricetulus migrodentorius: Wu, Fu, Yuan, Gao & Yue, the current Nothocricetulus, also Allocricetulus, Tscherskia, 2015: 44. Incorrect subsequent spelling for and Urocricetus, as they are defined in this volume. Some migratorius Pallas. authors classified such a heterogenous species assembly Cricetulus migrates: Esfandiari, Nahrevanian, Pourshafie, into different subgenera or species groups. Therefore, Gouya, Khaki, Mostafavi, Darvish & Hanifi, 2017: Argyropulo (1933b, c) recognized 2 species groups, no pagination; the name is consistently misspelled migratorius group which included also lama (now in throughout the entire paper. Urocricetus), and barabensis group. The grey hamster was Nothocricetulus migratorius: Lebedev, Bannikova, classified as the sole representative of the migratorius Neumann, Ushakova, Ivanova & Surov, 2018a: 343. species group by Ellerman (1941), Pavlinov & First current name combination. Rossolimo (1987) and Pavlinov (2003, 2006). Ellerman & Morrison-Scott (1951) also allocated barabensis and Etymology. Generic name is composed of ‘Nothos’ longicaudatus into the migratorius group. (Latin for ‘false’; Lebedev et al. 2018a) and Cricetulus, which is diminutive of Cricetus (i. e. the hamster). The Fossil history of Nothocricetulus is rather puzzling. name (false dwarf hamster) is allusion to a widespread Cricetulus migratorius of earlier authors is not sharply classification of migratorius as Cricetulus. Since Cricetulus delimited from the fossil Allocricetus. McKenna & Bell has barabensis as the type species, the inclusion of (1997) treated Allocricetus and Cricetulus s. lat. (i. e. with migratorius created paraphyletic group (see below). The the inclusion of migratorius) to be congeneric, while species epithet migratorius (from Latin ‘migrare’, Kowalski (2001) explicitly synonymized Allocricetus meaning ‘to migrate’) alludes to a presumed migratory bursae with migratorius. The earliest records of broadly nature of these animals, for which Pallas (1773: 703) defined Cricetulus are from the Early Pliocene (Island of reported to occur in steppes along the Ural River, but Rhodes, Greece; Turnbull 1975) and are succeeded by in certain years migrate in great numbers out of a desert material from the Middle Pliocene from Russia (“Occurit graminoſis Ia (Topachevskiy & Skorik 1992) and the Lower ı̏ kum, diciturque certis annis copioſiſſime e deſertis auentare …”). Johann F. Gmelin Pleistocene from Europe (Maul 1990). The proper provided similar account: “The Cossacks say that [the migratorius is stated for Anatolia since the Early Pliocene species] migrates out of the deserts in vast multitudes; (Alpaslan et al. 2009); European records are reportedly SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 69. from the Late Pliocene (Villanyian), Biharian and Distribution. The range is by far the largest of any Toringian (Kowalski 2001). There is considerable hamster species, encompassing 7,129,600 km2 and discrepancy among authors, however, and Toringian stretching from eastern Europe to eastern Nei Mongol and older material is frequently classified as Allocricetus (Figure 45). In the west, grey hamsters occupy Russia bursae. Vasileiadou & Sylvestrou (2022) still accept southward of the Volga and the Kama rivers; the Allocricetus as a genus in its own right, and reported A. northern-most occurrence is in Bol'shechernigovsky bursae until the Late Pleistocene of Europe and Turkey. rayon (Samara District; Simak 2009). From the vicinity of Samara, the range border steadily declines A high number of species of grey hamsters was southwards towards Ukraine where reaching the admitted during the 19th century. Pallas already western extension in Vizhnitskiy Rayon (Tatarinov recognized 4 species (migratorius, phaeus, accedula, 1973) on the eastern foothills of the Carpathian Mts.; arenarius), and by early 1900s a further 6 species were further south-east, the border follows this mountain added (cinerascens, isabellinus, fulvus, murinus, coerulescens, arch until reaching eastern Romania (Simionescu 1966). atticus). Taxonomy and nomenclature were revised by South of the Danube River, there are 2 isolates on the Thomas (1917) who relegated all these names to Aegean-Black Sea shore (1) in south-eastern Bulgaria subspecies (or synonyms) of a single polytypic species (Nedyalkov 2016) and adjacent Turkish Thrace migratorius. Thomas further concluded that “by a curious (Kryštufek & Vohralík 2009), and (2) in Greece. The fatality, not unusual in nomenclature” (p. 452), phaeus, Greek isolate is further fragmented in Thessaly, Central and not migratorius, was accepted as the oldest name for Greece (Sterea Ellada), Attica, and Peloponnesus grey hamsters (Thomas 1917). Some early authors, (Ondrias 1966, Bontzorlos 2009). Grey hamsters are however, synonymized migratorius with acredula (e.g. excessively scarce in these fragments, and majority of Gmelin 1788). records come from owl pellets both in Greece (Bontzorlos 2009, Bontzorlos et al. 2003) and Bulgaria Particularly puzzling was the identity of Cricetulus kozlovi (Nedyalkov 2016). Satunin, 1902, from Gansu which was for long known only from the type which consists of skin (Figure 50h) Between the Volga and Ob Rivers, hamsters do not and damaged skull (figured in Argyropulo 1933c: Figure move north of the 55th parallel; the most exposed 25, and Lebedev & Potapova 2008: Figure 5). The main occurrence is the Nizhneomsky district (Bakhrushev et source of confusion was a pseudo-sciuromorphous al. 2005). The exposed records, however, are widely type of zygo-masseteric structure, which induced isolated in northern Kazakhstan and adjacent south-various authors to accept kozlovi as a species in its own western Siberia; in Kazakhstan, the range becomes right (Argyropulo 1933b, c). Alternatively, kozlovi was contiguous only south of the 50th parallel (Shubin synonymized with Cricetulus barabensis obscurus (Allen 1977b). Eastward of the upper Irtysh River, the range 1940) or Urocricetus kamensis (usually ranked as one of its is shaped by the western slopes of the Altai Mts.; further subspecies; Wang & Cheng 1973, Corbet 1978, Wilson east, it is defined by the 45th parallel. The eastern-most & Reeder 1993, 2005, Zhang et al. 1997, Luo et al. 2000, range is in Mongolia (Bayanhongor, Dornogovi, Govi Wang 2003, Smith & Hoffmann 2008, Haslauer 2017d); Altay, Hovd, Ömnögovi) and in China between Nei some authors shifted kozlovi to the incertae sedis section Mongol and the middle and upper reaches of the of Cricetulus (Ellerman 1941, Ellerman & Morrison- Huang-He; the exposed eastern record is in Ar Horqin Scott 1951). Sokolov & Orlov (1980) suggested that Banner (Xu 2016). To the west of the Huang-He, the kozlovi is close to migratorius, and Lebedev & Potapova Chinese records are widely scattered across Ningxia, (2008) showed that a presumably unusual type of Qinghai, Gansu and Xinjiang (Zhang et al. 1997). To zygomasseteric architecture in kozlovi was well inside the west of Chinese Turkestan, the range sharply turns the variation range for migratorius. south reaching northern and western Pakistan (to the 70 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. guFi re 45: istrD ibu nal rtio an ge o f the g rey h am ster othoN tulus mcrice torius.igra SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 71. west of Indus) as far south as Sulaiman Mts. (Roberts Kazakhstan (Afanasiev 1953), Tajikistan (Davydov 1977). Further west, the grey hamster is present in 1988), and Pakistan (Roberts 1977). western and northern Afghanistan, the mountainous margins of the Iranian Plateau (Zagros, Alborz, Köpet Elevational range is from –25 in the Caspian Dag), northern Iraq (Al-Sheikhly et al. 2015), northern Depression up to 4,800 m in the Pamir Mts. (Davydov Syria (Aidek et al. 2025), the entire Levant coast 1988). There are considerable regional differences in (Tohmé & Tohmé 1985, Qumsiyeh 1996, Mendelssohn occupied elevations. In Europe, grey hamsters are tied & Yom-Tov 1999, Amr et al. 2018) as far south as to lowlands but ascend up to 2,300 m high in Anatolia Ma’an (southern Jordan; Obuch 2018), the entire (Kryštufek & Vohralík 2009) and Caucasus (Dal’ 1954, Anatolia (Kryštufek & Vohralík 2009), and the greater Alekperov 1966). Further east in Central Asia, their part of Trans-Caucasus in Azerbaijan, Armenia, and presence is common at 3,500–4,000 m of elevation eastern Georgia (Dal’ 1954, Shidlovskiy 1962, (Vinogradov et al. 1936, Janushevich et al. 1972, Alekperov 1966, Tembotov 1972, Bukhnikashvili Pavlenko & Allabergenov 1974, Ayzin 1979). 2004). Grey hamsters are present throughout Central Asia, i. e. in Kazakhstan (Shubin 1977b), Kyrgyzstan Grey hamsters were observed inside houses already by (Ayzin 1979), Tajikistan (Vinogradov 1935), Pallas (1779). So far, synanthropic populations have Uzbekistan, and Turkmenistan (Marinina 2005), as long been reported from European Russia (Minoransky et al. as suitable habitat is present. Hence, they are absent 1997), south-west Asia (Satunin 1905, Missone 1959), from large parts of the Karakum and Kyzylkum deserts including Armenia (Dal’ 1954), Azerbaijan (Alekperov in Uzbekistan and Turkmenistan (Marinina 2005), from 1966), the Caucasus (Vereschagin 1959, Tembotov coniferous forests in northern Kazakhstan, sandy 1960, Shidlovsky 1962), in Turkmenistan (Nurgel’dyev substrate south of the Balkhash Lake in eastern 1969), Kazakhstan (Afanasiev 1953, 1960, Shubin Kazakhstan (Shubin 1977b), and Dzungarian Basin in 1977b), Kyrgyzstan (Stogov 1951, Toktosunov 1958, Xinjiang (Zhang et al. 1997). Similarly, they are missing Janushevich et al. 1972, Ayzin 1979), Uzbekistan from hyper-arid deserts of Dasht-e Kavir and Dasht-e (Mukhamedkulov 1964, Pavlenko & Allabergenov Lut in Iran (cf. Yusefi et al. 2019). The grey hamster is 1974), Tajikistan (Davydov 1988), Pakistan (Roberts absent from the islands, but historically occupied the 1977), and Mongolia (Sokolov & Orlov 1980). In some Island of Barsake’lmes in the former Aral Sea (Shubin urban settlements, grey hamsters are as abundant as 1977b). The Quaternary range exceeded the current house mice (Mus) or rats (Rattus) (e.g. Shidlovsky 1962). one, stretching as far west as Spain and Great Britain (Kowalski 2001). Description. Similar to the long-tailed lesser hamster Cricetulus longicaudatus (Figure 46). Dimensions: body Grey hamsters occupy a wide range of open and dry mass = 25.5–70 g, length of head and body = 105–132 habitats like forest steppe, mountain steppe with mm, length of tail = 22–41 mm, length of hind foot = wormwood and juniper, steppe with cereal grasses, 17.0–20.0 mm, length of ear = 15.8–22.0 mm, deserts and semi-deserts which frequently hardly condylobasal length of skull = 25.4–31.2 mm, provide any shelter. They were collected from various zygomatic width = 13.0–16.9 mm, length of maxillary types of substrates, e. g. black and brown soils, fixed tooth-row = 3.7–5.1 mm; captive hamster weight up to sands, saline soils, clay, and stony ground. On barren 75 g (Volf & Volf 1993). Sexes are of approximately the slopes and mountain peaks they hide in screes and same size in Anatolia (Kryštufek & Vohralík 2009), among rocks and boulders. In Mongolian deserts they though some populations are dimorphic. In Central are frequently restricted to oases (Sokolov & Orlov Asia, males are heavier on average; the quotient of mean 1980). Grey hamsters occupy cultivations, including male / female body mass is 1.15 in Tajikistan (Davydov gardens and old orchards. In parts of their range, grey 1988) and 1.26 in Kyrgyzstan (Janushevich et al. 1972). hamsters inhabit dry forests or forest belts, specifically Contrary to this, Cheesman (1921) found females to be in Moldova (Lozan 1971), Crimea (Flerov 1929), on average larger than males in Shiraz (Iran). Tail is Kabardino-Balkaria (Tembotov 1960), west Siberia longer than hind foot, while its length is highly variable, (Bakhrushev et al. 2005), Kyrgyzstan (Ayzin 1979), accounting for 16–42% of length of head and body 72 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 46: Grey hamsters Nothocricetulus migratorius from Levashinskiy Rayon, Dagestan (a), and Homs, Syria (b). Photo courtesy of Magomed Magomerasulovich Chunkov (a) and Alenka Kryštufek (b) (usually ≈ 28%). Tail is parallel-sided and more densely band and whitish or black tip. White-tipped hairs clad than in Cricetulus (Figure 29d); terminal pencil is predominate in pale individuals and black-tipped hairs feeble (length ≈ 1 mm). Eyes are moderately large are more abundant, along with all-black longer hairs, in (diameter = 4.1–4.9 mm) and ears are long and circular; dark grey animals. Colouration of dorsal surface from they are densely hairy on the outer side and nude to muzzle to tail-base is either grey or buff. Grey hamsters sparsely clad with hairs on the inner side. Whiskers are vary from light grey to glaucus (bluish) grey and dim- long (up to 35 mm), white, brown or blackish. Palms grey, and buff animals have grey ground colour heavily and soles have 5 and 6 pads, respectively. Plantar pads admixed drab, buffy or brown (Figure 47). Black-tipped are of approximately the same size and the metatarsal hairs became conspicuous on the crown and along the pair is comparatively larger than in Cricetulus (Figure spine producing a fuzzy mid-dorsal streak (Figure 47). 33b). Fur is soft and dense, 7–11 mm long on mid-back Hairs on the underside are either white-to-base or have and 5–6 mm on belly; protruding sparse hairs are grey bases and white tips. All-white hairs usually cluster particularly long at tail base (Figure 29d). Summer fur is into irregular patches on the chin, throat, chest, armpits shorter than winter hairs. Hamsters moult throughout and the inguinal region. As the result, belly is a mosaic the vegetation season (Davydov 1988). Feet are thickly of pure white and grey clouded patches; rarely, the covered by short white hairs. Hairs of dorsal pelage are underside is shaded pale buff. Line of demarcation is typically tricoloured, with slate base, buffy subterminal well defined or sharp; it is slightly serpentine with white SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 73. underside turning dorsally between the rib cage and the Skull (Figure 48) closely resembles Cricetulus in size and hip (Figure 47a–c). Outer surface of fore feet is white proportions; width across zygomatic arches accounts and that of hind feet is of same colour as the back. Hairs for 49.3–58.0% of condylobasal length (mean = are frequently faintly tinged drab or light buff on the 53.5%). The most obvious difference between the two head, cheeks, on flanks and at tail base. Some genera is in (1) length of the squamosal suture and individuals have a white postauricular tuft. Ears do not interparietal suture, and (2) in the morphology of the contrast much with surrounding parts; they are zygomasseteric structure. In Nothocricetulus, the monochromatic grey and lack white rim which is squamosal suture (sutura squamosa cranii) is, in dorsal characteristic of Cricetulus. The tail is usually indistinctly view, longer than in Cricetulus that comes from different bicolour, darker above and paler below. Juvenile position of the fronto-temporal angle of the parietals hamsters are usually duller and greyer. relative to the orbit. The interparietal (sagittal) suture is shorter in Nothocricetulus and does not reach the Glans penis is wide, shallow and blunt at its peak; the posterior level of the orbit, whereas it is normally at that width approximately equals the length. Dorsal base has level in Cricetulus. Secondly, the zygomasseteric no bump (present in Cricetulus) and the central belt of structure is either myomorphous or pseudo- the glans has no spines. Spines cover the proximal and sciuromorphous (Figure 20d) in Nothocricetulus, but the distal parts of glans, and are present across the entire strictly myomorphous in Cricetulus (Figure 20g). The glans in Cricetulus. Both, Nothocricetulus and Cricetulus, myomorphous conditions are characterized by a more have 2 ventral papillae but lack dorsal papilla. Central extensive zygomatic plate with a straight vertical or papilla is slightly wider than lateral papillae in oblique anterior margin. Besides, keel of zygomatic Nothocricetulus, while the difference between these plate is prominent and zygomatic notch is deep; both papillae is prominent in Cricetulus (Vorontsov 1982). are seen in dorsal view (Figure 48). The pseudo-Baculum has a heavy proximal part with expanded base sciuromorphous type, on the other hand, shows a and comparatively small distal baculum (Figure 17e). reduced masseteric plate with emarginate margin, weak Dimensions (length): proximal baculum = 3 mm, lateral or no keel and absence of zygomatic notch. The distal baculum = 1 mm, medial distal baculum = 0.5 infraorbital foramen is more of oval shape in pseudo- mm (Argyropulo 1933c, Didier 1953). sciuromorphous type, but is expanded dorsally and constricted ventrally in the myomorphous type. All transitions exist between the two extremes in N. migratorius; besides, asymmetry in zygomasseteric type was also reported (Lebedev & Potapova 2008). Molars show similar pattern as in Cricetulus with some important differences. Metalophule (the antero-mesial ridge of metacone) contributes to the X-pattern of enamel ridges between the protocone-paracone and hypocone-metacone in M1–2. Mesolophid is present on the lingual side between the entoconid and metaconid of M3 (Figure 49). Karyotype: 2n = 22, NFa = 40, NF = 44; the autosomal Figure 47: Skins of grey hamsters Nothocricetulus migratorius in dorsal complement consists of 5 metacentric and 5 view to show colour variation across a distance of 450 km in subtelocentric pairs. In the conventionally stained Anatolia (Turkey): a, b – Ermenek, Karaman Province; c, d – mitotic preparations, the sex chromosomes appear as Şarkışla, Sivas Province. Note dark spinal stripe which terminates on the front as crown patch. Vouchers (a–c) show dorsad expansion isomorphic large subtelocentric elements but show a of white fur between the rib cage and the hip (compare to Urocricetuls distinct internal structure, including slightly different lama on Figure 102). centromere position. Various studies reported 74 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 48: Skull and mandible of grey hamster Nothocricetulus migratorius from Sivas, Turkey. Abbreviation: fta – fronto-temporal angle of the parietals; ssc – sutura squamosa cranii. differences in size of individual chromosomes and in Variation and Subspecies. Phylogenetic analysis the position of centromere in the small autosomal pair based on mtDNA retrieved 3 deeply divergent allopatric (reviewed in Arslan & Zima 2014). Besides, lineages, which presumably originated from trichotomy heteromorphy of homologous chromosomes was at the end of the Middle Pleistocene ~ 130–160 kya retrieved in at least two chromosomal pairs in several (Lebedev et al. 2018a). The West lineage contains different populations (Yerganian & Papoyan 1965, hamsters to the west of the Volga River in Europe, the Kartavtseva 1985, Brandler & Blekhman 2024). Caucasus and Asia Minor, while the East lineage Brandler (1999) reported a population from the comprehends samples to the east of the Volga in Tianshan Mts. with 2n = 24, NF = 46. The sex Eastern Europe and Asia, as far west as Iran. The West chromosomes are heteromorphic; the X chromosome lineage is further structed into 4 allopatric sublineages, is medium-sized submetacentric and the Y which evidently split during the early Last glacial cycle chromosome is acrocentric of similar size (Brandler & at ~ 80 kya: (1) the European sublineage, which is Blekhman 2024). widespread to the north of the Sea of Azov–northern Figure 49: Grinding pattern of upper (a, b, c) and lower (a’, b’, c’) molars in grey hamsters Nothocricetulus migratorius: a – Kochkor District, Kyrgyzstan; b – Mongolia; c – Sivas, Turkey. me – metalophule; md – mesolophid. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 75. coast of the Caspian Sea line; (2) the cis-Caucasian Ellerman & Morrison-Scott 1951, Vinogradov & sublineage from the steppes between foothills of the Gromov 1952, Gromov et al. 1963, Kuznetsov 1965); north-Caucasus and the Azov–Caspian line; (3) the regional studies similarly returned high numbers of Armenian sublineage, and (4) the Anatolian subspecific taxa, e. g. 5 subspecies for each, the sublineage; the last holds sister position against the Caucasus area (Shidlovskiy 1962) and Kazakhstan remaining West haplotypes. Contrary to this situation, (Afanasiev 1960), 3 subspecies for Kyrgyzstan the East lineage shows minimal structure. These 2 (Toktosunov 1958), 2 subspecies for a comparatively major lineages were originally identified by 2 putatively small area in northern Pakistan (Siddiqi 1969), and so diagnostic allozyme loci out of 8 polymorphic loci forth. Subspecies were diagnosed by fur colouration studied (Lebedev et al. 1998, 2000, Mezzherin 2001). and size. Grey hamsters tend to be paler where climate Furthermore, multivariate analysis of size-adjusted is arid and darker in more humid conditions (Figures 47 cranial measurements similarly retrieved 2 major & 50). E. g. in Anatolia, dull-grey hamsters (classified as population clusters, which were also separated by the ssp. vernula) occupy the Black Sea coast, while buffy-Volga River (Lebedev et al. 1998, 2000). The 3rd major greyish hamsters (cinerascens) live inland in regions phylogenetic lineage from the Qurama Mts. (south- receiving less rain (Kryštufek & Vohralík 2009). western end of the Tianshan range flanking north- western Fergana Valley, Uzbekistan) is also Similarly, in Tajikistan, pale hamsters with ample sandy characterized by a distinct cytotype (2n = 24), but its tints (ognevi) live at lower elevations, while darker morphology is not known at the time of writing. hamsters (coerulescens) inhabit higher elevations (Davydov 1988). At large scale, pale sandy-buff Earlier authors recognized 12–15 subspecies of grey hamsters (caesius, coerulescens) are typical of the hamsters (Pidoplitshka 1928, Argyropulo 1933b, c, mountains of Central Asia (Janushevich et al. 1972), Ellerman 1941, Vinogradov & Argyropulo 1941, while grey hamsters ( bellicosus, zvieresombi) occupy black- Figure 50: Skins of grey hamsters Nothocricetulus migratorius from different parts of their range to show variation in fur colouration. Parenthesized are subspecific names which were traditionally used to define the particular sample. a – Criulensk District, Moldova (bellicosus); b – Ankara, Turkey (cinerascens); c – Volgograd District, European Russia (phaeus); d – Ayagoz, eastern Kazakhstan (caesius); e – Ustyurt, Qoraqalpogiston, Uzbekistan (migratorius); f – Hisar Range, Tajikistan (coerulescens); g – Kopal'skiy Uezd, Semirechye, northern foothills of Dzungarian Alatau, south-eastern Kazakhstan (cinereus); h – Nanshan, Gansu, China (type of Cricetulus kozlovi; ZIN 5831). In line with subspecific taxonomy proposed in this volume, samples a–c classify as phaeus and samples d–h as migratorius. 76 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. soil regions of Ukraine (Pidoplitshka 1928). Size Lebedev et al. (2018b), the 2 major subspecies differences among populations and putative subspecies (migratorius and phaeus) are more likely subspecies groups may be considerable. E. g. in Kazakhstan, body mass or semi-species (Lebedev 2012). In any case, refinement reaches 45 g around the Balkhash Lake and 65 g in of subspecific taxonomic remains a task for further southern Kazakhstan (Shubin 1977b). taxonomic revision. Gray hamsters are on average the largest (mean Nothocricetulus migratorius condylobasal length of skull >27 mm) in the migratorius (Pallas, 1773) mountainous regions of Central Asia (Lebedev 2000), specifically in Turkmenistan (Zykov 1991, Marinina 2005), Afghanistan (Niethammer 1982), eastern Synonyms: Mus arenarius Pallas, 1773; Mus accedula Kazakhstan (Shubin 1977b), northern India (Agrawal Pallas, 1779; Cricetus isabellinus Filippi, 1865; Cricetus 2000) and China (Luo et al. 2000). Hamsters living fulvus Blanford, 1875; Arvicola coerulescens Severtsov, northward and westward are smaller on average (mean 1879; Cricetulus kozlovi Satunin, 1902; Cricetulus condylobasal length <26.5 mm). Outliers, however, migratorius griseus Kashkarov, 1923 (replaced by cinereus were reported; Kashkarov, 1926); Cricetulus migratorius caesius e. g. grey hamsters occupying Ukraine and adjacent Russia have larger skulls (condylobasal Kashkarov, 1923; Cricetulus migratorius pamirensis length > 27.0 mm) (Pidoplitshka 1928, Migulin 1938) Vinogradov 1931; Cricetulus migratorius ognevi Vinogradov than expected from their geographical position. & Argyropulo, 1941; Cricetulus migratorius elisarjewi Ellerman (1961) stressed variation in the length of Afanasiev, 1953. upper tooth-row. Indeed, hamsters from the mountainous regions of Central Asia also have longer Distribution: Eastern Europe (to the east of the Volga molars (mean length >4.15 mm) than those from River); Iran (border against ssp. phaeus not resolved), Siberia, western Kazakhstan, the Middle East and and the rest of range in Asia. Europe (<4.20 mm). The overlap is considerable; e. g. the range in Kazakhstan is 4.1–4.5 mm on the east of Characteristics: Diagnosed by cytb and cytochrome the country oxidase I (coI) gene sequences and by 2 fixed alleles for v. 4.0–4.3 elsewhere (Shubin 1977b). External and cranial ratios similarly show variation at Ck-2 and s-Ord loci (Lebedev et al. 1998, 2000). various spatial scales. Length of tail relative to length of Karyotype: 2n = 22, NF = 44; sex chromosomes are head and body varies individually (Kryštufek & isomorphic (Arslan & Zima 2014). Rostrum is more Vohralík 2009) and regionally ( gracile, longer and shallower, upper incisors are e. g. Janushevich et al. 1972). Similarly, width-to-length of skull changes both narrower, nasals are longer, tympanic cavity is more within the same population (Kryštufek & Vohralík swollen, interorbital region is wider, and braincase is 2009) and between regions (Ellerman 1961). The west- shorter and narrower (Lebedev 2000). structure. More than 35% of grey hamsters from Nothocricetulus migratorius phaeus to-east trend is also seen in the zygo-masseteric Mongolia have pseudo-sciuromorphous structure v. (Pallas, 1779) <12% of those occurring westward (Lebedev & Potapova 2008). Many authors stressed great variation Synonyms: Hypudaeus cinerascens Wagner, 1848; Cricetus in morphological traits (Toktosunov 1958, Ondrias murinus Severtsov, 1873; Cricetulus atticus Nehring, 1902; 1966, Davydov 1988) and loose subspecific diagnoses Cricetulus tauricus Satunin, 1908 (nomen nudum); (Bannikov 1954, Shubin 1977b, Sokolov & Orlov Cricetulus arenarius bellicosus Charleman, 1915; Cricetulus 1980). As traditional subspecies are frequently at odds arenarius vernula Thomas, 1917; Cricetulus falzfeini with morphologically diagnosable populations, no Matschie, 1918; Cricetulus migratorius pulcher Ognev, 1924; subspecies are recognized in recent reviews (e. g. Cricetulus migratorius neglectus Pidoplitshka 1928; Cricetulus Haslauer 2017a). In spite of this, we subsequently migratorius zvieresombi Pidoplitshka, 1928; Cricetulus propose a crude subspecific division, which is mainly migratorius phaeus sviridenkoi Pidoplitshka, 1928 (invalid based on the results of Lebedev and coworkers as infrasubspecific taxon). (Lebedev 2000, Lebedev et al. 2018b). As suggested by SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 77. Distribution: Europe to the west of the Volga River; The year of publishing Allocricetulus is sometimes stated the Caucasus, Anatolia and the Levant coast; border as 1932 (Pavlinov & Rossolimo 1987: 170, Lebedev against the nominotypical subspecies not resolved. 2012: 215), although the issue of the Proceedings of the Zoological Institute in Leningrad for 1932 with 2 Characteristics: Diagnosed by cytb and cytochrome papers by Argyropulo (1933a, b) was seemingly released oxidase I (coI) gene sequences and fixed alleles for Ck-2 in 1933 (Baranova & Gromov 2003: 48). Besides, and s-Ord loci (Lebedev et al. 1998, 2000). Karyotype: Argyropulo (1933b: 243) himself dated his Cricetus 2n = 22, NF = 44; sex chromosomes are isomorphic cricetus fuscidorsis, which was published in the same (Arslan & Zima 2014). Rostrum is more robust, shorter volume of the Proceedings, as being released in 1933. and deeper, upper incisors are broader, nasals are Gromov et al. (1963: 503) erroneously gave the year of shorter, tympanic cavity is less inflated, interorbital publishing Allocricetulus as 1937. region is narrower, braincase is longer and wider (Lebedev 2000). Allocricetulus was established as a subgenus of Cricetulus (Argyropulo 1933b). Prior to this, Eversmann’s Nothocricetulus migratorius unnamed hamsters were classified in the genus Cricetulus without subspecies further subgeneric ranking (Trouessart 1910, Martino & Martino 1916, Beljaev 1933). Less often, Allocricetulus Distribution: was synonymized with Nothocricetulus migratorius Known from the Angren Plateau (Qurama Mts.) in south-western end of the Tianshan (Thomas 1917, Allen 1925) or included into Mesocricetus range, Uzbekistan. (Ogneff 1925, Pidoplitshka 1928, Kouznetzof 1928, Argyropulo 1931). Vinogradov & Gromov (1952, 1956) Characteristics: classified Eversmann’s hamsters into Cricetus; Diagnosed by cyt b and cytochrome oxidase Stroganova (1954) and Popov (1960) kept Allocricetulus I ( coI ) gene sequences (Lebedev et al. 2018b). Karyotype: 2n = 24, NF = 46; sex chromosomes are as a subgenus of Cricetus. Ellerman (1941: 429) classified heteromorphic (Brandler & Blekhman 2024). Eversmann’s hamsters into the eversmanni group within Morphology is not known (Lebedev et al. 2018b). Cricetulus, though subsequently (p. 435) accepted Allocricetulus as a valid subgenus. GENUS: Allocricetulus Argyropulo, Allocricetulus was elevated to a genus in its own right 1933 – Eversmann’s hamsters already in the early 1940s (Vinogradov & Argyropulo 1941). This was widely accepted by Russian and some Allocricetulus Argyropulo, 1933b: 242. Type species by Eastern authors (Flint et al. 1965, Stubbe & Chotolchu original designation is Cricetulus eversmanni Brandt. 1968, Vorontsov & Krjukova 1969a, Yudin et al. 1979, Argyropulo proposed Allocricetulus as a subgenus of Sokolov & Orlov 1980, Gromov & Baranova 1981, Cricetulus. Kartavtseva & Vorontsov 1992, Gromov & Erbajeva 1995, Gromov et al. 1963, Pavlinov & Rossolimo 1987), Etymology. The name Allocricetulus was coined from while part of Russian authors (Shnitnikov 1936, ‘allos’ (Ancient Greek for ‘other’ or ‘strange’) and Kuznetzov 1944, Kuznetsov 1948, 1975, Afanasiev Cricetulus, which is diminutive of Cricetus (the hamster), 1953, Bannikov 1954, Stroganova 1954, Vorontsov i. e. a ‘strange small hamster’. 1960, Karaseva 1963) and the majority of Western (Corbet 1978, Corbet & Hill 1980, 1986, Honacki et al. Taxonomy and Nomenclature. Allocricetulus has no 1982, Zima & Král 1984) and Chinese authors (Zhang vernacular name in English. By using ‘Eversmann’s et al. 1997, Luo et al. 2000, Fu et al. 2005, Wu & Fu hamsters’ as generic name we follow Russian authors 2005) continued to report Eversmann’s hamsters as (Gromov et al. 1963, Flint 1966b, Shubin 1977d, part of Cricetulus, thought frequently at a subgeneric Sokolov & Orlov 1980, Gromov & Baranova 1981, rank. The concept of Allocricetulus as a genus Gromov & Erbajeva 1995). independent from Cricetulus has been widely accepted 78 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. since 1990 (Kowalski 2001, Wang 2003, Jiang et al. with Cricetulus, and simultaneously treated Allocricetulus 2015). as a genus in its own right. From cladistic analyses based on molar cuspidation in fossil taxa (which did not The actual phylogenetic position of Eversmann’s include Allocricetulus), Bescós (2003) concluded that hamsters is contested (Figure 1). Gromov et al. (1963) Allocricetus includes fossil species Allocricetus jesreelicus exposed a mosaic nature of their morphology. In the Bate, 1943, and Allocricetus teilhardi Zheng, 1984, which shape of limb bones, Allocricetulus is intermediate to clustered with Nothocricetulus and Cricetus, rather than Cricetulus and Cricetus, while its cranial shape resembles with Allocricetus bursae (as the genotype). From the “small Mesocricetus”. Morphology of bullae suggests a results of Bescós (l. c.) one can conclude that Allocricetus sister position against the clade of Cricetulus + is a crown cluster in the phylogenetic tree of hamsters Nothocricetulus (Potapova 2005). In Allocricetulus and part and also a composite of several genera. Stuart (1991), of Nothocricetulus, the anterior portion of lateral masseter on the other hand, suggested conspecificity between (masseter lateralis anterior) reaches rostrum, hence the Allocricetus bursae Schaub, 1930, and Cricetiscus sungorus. zygomasseteric structure is of pseudosciuromophous In any case, the identity and scope of Allocricetus is type (Lebedev & Potapova 2008). Ross (1992) loosely understood; for a detailed discussion on its suggested for Eversmann’s hamsters to hold a sister status, see Horáček & Lebedová (2022). Fossils of A. position against Cansumys + Tscherskia + Cricetus + eversmanni are reported from the Middle (Gromov & Mesocricetus, while chromosomal data clustered Baranova 1981) and Late Pleistocene (Kowalski 2001); Allocricetulus inside Cricetulus + Nothocricetulus + Cricetus McKenna & Bell (1983) quote no fossils at all. (Romanenko et al. 2007). Sequence data retrieved a sister position of Allocricetulus and Cricetus (Lebedev Number of species in Allocricetulus was still disputed in 2018a, Ding et al. 2020). In spite of the obvious recent times. The main source of disagreement is the differences in external and cranial morphology between position of Eversmann’s hamsters from Zaysan Basin Allocricetulus and Cricetus, these genera have several (east Kazakhstan), which are referred to as characteristics in common: (1) well developed torus pseudocurtatus. These hamsters externally resemble linguae and sulcus semilunaris, (2) medial sulcus which ends curtatus, but have the karyotype of eversmanni, and were before the tip of the tongue; (3) the borderline fold in the past either interpreted as conspecific with (margo plicatus) of the stomach is convoluted, and the eversmanni or transitional between the two species. corneous epithelium extends into the glandular portion, Depending on this view, different authors considered but not beyond the isthmus; (4) 3 ampullae coli, (5) Allocricetulus either as a monotypical (sub)genus comparatively short intestine (ratio of intestine to head (Kuznetsov 1932, 1965, Allen 1940, Kuznetzov 1944, and body is less than 4.5), (6) a postponed exposure of Mitina 1959, Bannikov 1954, Ellerman & Morrison- dentin on enamel ridges which separate 2nd internal fold Scott 1951, Ma et al. 1987, Zhang et al. 1997, Fu et al. (if2) from 2nd primary fold in M1–2, (7) pterygoid 2005, Wu & Fu 2005) or to contain 2 species platform is below (i.e. dorsad to) the level of palate (Argyropulo 1933b, c, Ellerman 1941, Vinogradov & (Ross 1992), (8) coronoid processus of the mandible is Argyropulo 1941, Gromov et al. 1963, Flint 1966b, powerful, and (9) karyotype is characterized by low Stubbe & Chotolchu 1968, Kuznetsov 1975, Corbet diploid number and specific pattern of differentially 1978, Sokolov & Orlov 1980, Gromov & Baranova stained chromosomes (Romanenko et al. 2007). 1981, Honacki et al. 1982, Corbet & Hill 1986, Pavlinov & Rossolimo 1987, Musser & Carleton 1993, 2005, Several authors argued that living Eversmann’s Gromov & Erbajeva 1995, Wang 2003, Lebedev 2012). hamsters are closely related to the fossil Allocricetus Strong evidence in support of a 2-species solution of Schaub, 1930. Thus, Gromov & Baranova (1981) Allocricetulus emerged already from chromosomal suggested that Allocricetus is the most probable direct studies by Matthey (1960) and Vorontsov (1960). ancestor of A. eversmanni and might be congeneric with Musser & Carleton (2005: 1040), however, called for Allocericetulus; this was categorically rejected by Ross fresh perspective to validate the specific status of (1992). McKenna & Bell (1983), Kowalski (2001) and curtatus, which is summarized in Gureeva (2022). Based Horáček & Lebedová (2022) synonymized Allocericetus on her results, we accept 2 species of Eversmann’s SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 79. hamsters: eversmanni and curtatus. They differ in diploid Distribution. Steppes and semideserts between the number and the morphology of chromosomes (2n=20 Volga River and eastern Gobi Desert at 117°E in China; in curtatus and 2n=26 in eversmanni; Romanenko et al. the eastern-most records are in Hebei. In the north, 2013), cranial morphology (Gureeva et al. 2020), Eversmann’s hamsters reach the 56th parallel in Russia; morphology of glans penis and baculum (Vorontsov the southern border is tentatively set by deserts of 1982), and in nucleotide sequences of mitochondrial Central Asia in Kazakhstan, the Mongol Altai Mts. and and nuclear genes (Neumann et al. 2006, Gureeva 2022, Gobi Altai Mts. (Mongolia) and the Huang He River Meschersky et al. 2024). Their ranges are allopatric as (north China). they are separated by the Dzungarian Govi and Mongol Altai Mts. (see distributional maps below). Evolutionary Characteristics. Medium-sized hamsters with divergence between the two species is estimated at 120 moderately long snout (Figures 51, 56, 59); the tail kya, however, the confidence interval is wide (CI = 50– which accounts for approximately 1/5 of head and body 212 kya). length (tail relative to head and body = 14–22%) is proportionally longer in juveniles. In both species, Contrary to earlier views on a complete reproductive males are on average by 20% heavier than females isolation between eversmanni and curtatus (Vorontsov (Gureeva et al. 2016). Ears are of modest length, 1982), these species did hybridize in captivity, though rounded and covered by short hairs (Figure 8). Hind pregnancy frequently failed. Next, the F1 hybrids were foot is short, only slightly longer than the ear; the toes by 15–35% smaller than parental species and yielded no are comparatively shorter than in the remaining litters. Meiosis in hybrids has been disrupted during Cricetina. There are 4 fingers on the front paws, pachytene (prophasis I). Some spermatocits did equipped with comparatively weak claws; the thumb is develop into spermatozoa, however, the fertility in F1 rudimentary. The 5 palmar pads are comparatively males has been reduced (Gureeva et al. 2016). large; interdigital pads are about ½ size of metacarpal Relationships between eversmanni s. str. and pseudocurtatus pads. The posterior thumb does not differ appreciably are further discussed below in the account of A. in size from finger V, and fingers II–IV are of eversmanni. approximately same length. Hind claws are slightly Figure 51: Skins of Eversmann’s hamsters Allocricetulus: A. eversmanni (Saratov, Lower Volga, Russian Federation) and A. curtatus (south of Nomgon sum, Mongolia) in dorsal, lateral and ventral views. Photo: B. Kryštufek 80 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 52: Skull and mandible in Eversmann’s hamsters Allocricetulus: A. eversmanni (Volga Region, Russian Federation) and A. curtatus (Lake Orok-nor, Mongolia) in dorsal, lateral and ventral views. heavier than the front ones. Plantar pads are small, papillae; horny spines are restricted to the apex. The particularly so the metatarsal pair and the interdigital central and the 3 ventral papillae are prominent and pad III. Plants are hairy posterior to pads (Figure 33c). visible from the outside (Vorontsov 1982). Baculum is Fur is soft and fairly short, interspersed with numerous ossified but tips of the trident remain cartilaginous all-black hairs which usually protrude by 0.5–2 mm. The (Figure 17f, g); distal trident is proportionally long (65– long protruding hairs are numerous at the tail base, 76% of the length of proximal shaft). Manubrium is producing a conical appearance (Figure 51); the tail, expanded both laterally and ventrally, and can be however, is sparsely hairy and with no real terminal tuft. notched basally; width across the lateral expansions of The dorsum is uniformly brown to sandy-buff, belly is the shaft’s base accounts for 72–94% of its length. The white and the demarcation is sharp. central digit of trident is usually shorter than the lateral ones (Vorontsov 1982, Ross 1992). Females have 8 nipples each (2 pairs of pectoral and 2 pairs of inguinal nipples). Glans penis is barrel-shaped The skull is rather robust, though it lacks prominent and covered for the major part by furrows, ridges and bony ridges (Figure 52); zygomatic arches are rounded SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 81. and moderately expanded (zygomatic width accounts postponed relative to the lingual side of if2 (Figures 57 for 53–59% of condylobasal length), braincase is short & 60). and circular, rostrum is rather short and stout. Occipital condyles only slightly project beyond occiput and are therefore hardly seen in dorsal projection. The palate is proportionally long; the incisive foramina terminate well before reaching the level of M1, and interpterygoid fossa does not extend to the level of M3; the pterygoid platform is below (i.e. dorsad to) the level of palate. Bullae are fairly small and rounded; the interparietal is wide but reduced in length. Anterior margin of masseteric plate is straight or emarginated; the infraorbital foramen, zygomatic notch and the keel of zygomatic plate are not visible in dorsal view; the zygomasseteric structure is of pseudo-sciuromophous Figure 54: Caudal view of mandibulae of Mongolian Eversmann’s hamster (Allocricetulus curtatus). type (Lebedev & Potapova 2008). In frontal view, the infraorbiral foramen resumes oval shape (Figure 20e). Key to species Some authors (Popov 1960, Ross 1992) cite a W-shaped coronal suture as diagnostic for Allocricetulus. Indeed, 1a) Dorsal fur usually brownish (Figure 56), ventral this suture frequently displays irregular anteriorly side usually with a sternal streak which is of same oriented projection at the anterior margin of colour as the back1 (Figure 51); glans penis is interparietal, therefore giving the impression of the parallel-sided in dorsal view (width-to-length ratio letter ‘W’. Shape of coronal suture is, however, highly = 0.63), without ventral medial groove; central variable and the bulge is sometimes absent (Figure 53). papilla ventralis smaller than papillae laterales; papilla Bullae are of moderate size. Mandible is long and lateralis without lateral expansion; distal baculum shallow with well-developed processes; the coronoid with central digit obviously shorter than lateral process is prominent and extends back to the anterior digits (Figure 17f); interorbital width ≤ 4.9 mm; margin of mandibular condyle; the blunt alveolar interparietal ≥ 4-times as wide as long; 2n = 26; process is present on the outer wall of mandibular present to the west of the 89th meridian in Russian ramus at the level of caput mandibulae (Figure 54). Federation, Kazakhstan and northern Xingjian (China) …..…………………….…..… eversmanni 1b) Dorsal fur greyish-sandy (Figure 59), ventral side plain white (Figure 51); glans penis in dorsal view with rounded body and narrowed base and tip (width-to-length ratio = 0.80), ventrally with a shallow medial groove; central papilla ventralis approximately of same size as papillae laterales; papilla lateralis with lateral expansion (Г-shaped); distal baculum with central digit nearly as long as lateral digits (Figure 17g); interorbital width ≥ 4.9 eversmanni (top) and A. curtatus (bottom). Abbreviations: fr – frontal th 20; present to the east of the 89 meridian in bone, Figure 53: Variation in shape of coronal suture in Allocricetulus mm; interparietal < 4-times as wide as long; 2n = pa – parietal bone. Anterior is to the top; not to scale. Mongolia, China (absent in northern Xingjian), Upper incisors are orthodont and on the anterior side and marginally in Russian Federation (Tyva) embedded in orange enamel. M ………………………………………..… curtatus 1 , and frequently also M2, have internal fold 2 (if2) isolated from primary fold 1 Population from the eastern Zaysan Basin is of same colouration as 2 ( pf2 ) by enamel ridge; the ridge, however, is shallow, A. curtatus hence the abrasion of its dentin is significantly 82 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Allocricetulus eversmanni (Brandt, Cricetulus eversmanni belajevi Selewin, 1934: 77. For type 1859) – Common Eversmann’s hamster locality (“Бассейн р. Токрау, б. Каркаралинского округа”) and spelling see comments under belajevi Cricetus eversmanni Brandt, 1859: 210. Type locality (“in Nomenclature below. The two names, Argyropulo, 1933b (above), and the account on provincia Orenburgensi”) was subsequently are based on the same voucher (ZIN 78702) beljaevi and restricted to “Окресности г. Оренбурга к северу and are therefore objective synonyms. belajevi, [Cr]icetulus eversmanni: 1870). Vinogradov & A[llocricetulus] e[versmanni] microdon: Satunin, 1905: 340. Name Argyropulo, 1941: 169. Name combination. combination. A[llocricetulus] e[versmanni] beljaevi: north of the city]”, Russian Federation (Mitina 1959: 168. First use of the current name combination. от города [Neighbourhood of Orenburg to the Allocricetulus eversmanni: Vinogradov& Argyropulo, 1941: Mesocricetus eversmanni 1917: 453. Name combination and new status. : Stroganova 1954: 63. Cricetus (Allocricetus) eversmanni Ogneff, 1925: 13. Name Name combination. combination. Cricetulus eversmawni: [Cricetulus migratorius migratorius] eversmanni: Thomas, Argyropulo, 1941: 169. Name combination. Vinogradov & Mesocricetus microdon Ogneff, 1925: 14. Type locality: “бл. subsequent spelling of Karaseva, 1963: 211. Incorrect Пономаревки Бугурусланского у Самарской губ” Vorontsov & eversmanni Brandt. Allocricetulus eversmanni beljaevi pseudocurtatus [near Ponomarevka, Buguruslanskiy uezd (Distict), Samara Governorate]”, Russian Federation. Зайсанской котловины, п Krjukova, 1969a: 99. Type locality: “Восток Cr[icetulus] ev[ersmanni] microdon: Kuznetsov, 1932: 94. км к северу от с. Улькен eски Айгыр-Кум в 10 -Каратал [eastern Zaysan Name combination. Cr[icetulus] (Allocricetulus) eversmanni: Argyropulo, 1933b: village Ul’ken-Karatal]”, eastern Kazakhstan. Basin, Aygyr-Kum sands, 10 km north form the 245. Name combination. For 1933 as the year of Invalid as infrasubspecific taxon (natio); validated in publication (instead of 1932) see the generic account Kartavtseva & Vorontsov (1992; see below). above. C Cr[icetulus] (Allocricetulus) eversmanni microdon: Incorrect subsequent spelling of [ricetulus] e[versmanni] beljewi Zhang et al. 1997: 215. Argyropulo, 1933b: 245. Name combination. [ beljaevi Argyropulo. Cr[icetulus] (Allocricetulus) eversmanni beljaevi Argyropulo, Vorontsov 1992: 10. Type locality not specified, All ocricetulus] ev[ersmanni] pseudocurtatus Kartavtseva & 1933b: 245. Type locality: “Зайсан [Zaysan]”, also however, the only karyotyped individual was from spelled “Saissan” ( e. g. Argyropulo, 1933c: 137, “Agir Kum sands in the east Zaissan hollow (the Ellerman 1941: 435). In the account on North-West of the Zungaris [typographic error for Nomenclature (below) we argue that Argyropulo’s statement of the type locality is erroneous. The Vorontsov & Krjukova. Dzungaria])”. First appropriate naming of pseudocurtatus name beljaevi was based on the same type specimen as Selewin’s belajevi (see below). Correct type locality The species epithet is eponym to Russian Etymology. is provided in Selewin (1934: 77): “ Бассейн р. physician and naturalist of German ethnicity Alexander Токрау, б. Каркаралинского округа” ( in the Eduard Friedrich Eversmann (1794–1860). Eversmann original Russian version) and “Wasserbecken des was the first to describe A. eversmanni (as Cricetulus Flusses Tokrau des Bezirks von Karkaralinsk” phaeus ). Brandt based his 1859 description on vouchers (German text; Selewin 1934: 87), i. e. River Tokrau collected and reported by Eversmann (1850). in the Karkaray (Karkaralinsk) District in the Cr Karaganda (Qaraghandy) Region, Kazakhstan. Baranova & Gromov (2003: 48) Nomenclature. [ icetulus ] (Allocricetulus) eversmanni beljawi: Argyropulo, designated lectotype of A. eversmanni (voucher ZIN 1933c: 137. Incorrect subsequent spelling of beljaevi 4578; Eversmann’s collection No. 2998), which Argyropulo. 1933b. Argyropulo (1933c) correctly reportedly originates from “ Караульная гора, spelled the name (as beljaevi ) on p. 149 of the same Оренбург [ Mt. Karaul'naya gora, Orenburg]”. This work. See also comments below in the account on locality cannot be precisely located because during the Taxonomy and nomenclature. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 83. Figure 55: Distributional range of the common Eversmann’s hamster Allocricetulus eversmanni. 18th and early 19th centuries, the toponym Karaul’naya 120) and Mitina (1959: 1872). In German edition of gora was frequently used around Orenburg for any hill Argyropulo’s paper (1933c), the name was incorrectly or flat-top mountain. Eversmann (1850: 147) stated for spelled beljawi. It therefore happened that the his vouchers that they originated from the vicinity of misprinted name beljawi entered the mainstream Orenburg. This is also inscribed in the original label of literature while the name beljaevi was erroneously the lectotype (Baranova & Gromov 2003: 48) and was attributed to Kuznetzov (1944) (cf. Ellerman & reported already by Brandt (1859: 210). Morrison-Scott 1951: 626, Musser & Carlton 2005: 1040). The correct spelling is beljaevi as published in Type locality of A. eversmanni was frequently reported as Argyropulo (1933b) and not in Kuzyakin (1944), while “Киргизская степь (Казахстан) [Kyrgyz Steppe, beljawi is an incorrect subsequent spelling of beljaevi, Kazakhstan]” (Argyropulo 1933b, 1936), which was erroneously introduced by Argyropulo “Kirgisensteppe” (Argyropulo 1933c), “степь сев. (1933c). Казахстана [steppes of northern Kazakhstan]” (Kuznetzov 1944: 322), “Northern Kazakhstan Relations between beljaevi Argyropulo and belajevi Steppes” (Ellerman & Morrison-Scott 1951: 626), and Selewin have never been properly resolved. Pavlinov & “Khirgis Steppe” (Ross 1992: 257). “Kyrghiz” Rossolimo (1987: 170) claim that beljaevi Argyropulo (“Kirghiz”) is an old Russian word for the Kazakh and belajevi Selewin are based on different types, each Steppe which currently defines a vast grassland in with its own type locality: Zaysan for beljaevi and Tokrau northern Kazakhstan and adjacent Russia; Orenburg is for belajevi. Hence, Pavlinov & Rossolimo did not situated on the north-western edge of the region. consider these names to be homonyms “although they represent different Latin transliterations of the same In the English abstract of her paper, Mitina (1959: family name [Beljaev]”. We disagree with this 1875) restricted the type locality to “environs of the interpretation. Firstly, Argyropulo (1933b, c) did not town of Samara”. This contradicts her conclusion in the designate the type or the type locality for beljaevi. He main Russian text and is obviously due to an error. claimed, however, that his research was conducted “in the Zoological Institute of the USSR Academy of There is a great deal of confusion around the names Sciences (ZIN), using its collections” (our translation beljaevi, beljawi and belajevi. All these names are eponyms from Russian; Argyropulo 1933b: 239). Pavlinov & for A. M. Beljaev hence the correct spelling is beljaevi. Rossolimo (1987: 170) concluded, presumably on this This is how the name was firstly published by ground, that the type of beljaevi is kept in ZIN. Their Argyropulo (1933b) and used shortly afterward by presumption, however, was categorically rejected by Beljaev (1933: 36) himself; see also Argyropulo (1936: Baranova & Gromov (2003: 48) who further showed 84 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. that in the early 1930s ZIN was not in possession of a there into the Neolithic and Chalcolithic (Lozan 1971). single voucher of A. eversmanni collected in Zaysan. Since 1950, a decline was reported from European With A. e. beljaevi, Beljaev (1933: 36) referred to “Agr. Russia (Oparin 2005) and at present the species is of [obviously a misspelled abbreviation of Argyropulo] in conservation concern in 7 administrative districts of the litt [in litteris]”, therefore he evidently received the Russian Federation: Bashkhortostan, Tatarstan, information on a new taxon from Argyropulo, while the Astrakhan, Kurgan, Samara, Ulyanovsk, Chelyabinsk publication was still in press. More importantly, Beljaev (Vakhrushev & Sidorov 2011); all districts except was aware of a single locality for beljaevi, i.e. “б. Kurgan are from the European part of the Federation. Каркаралинский у.” (former Karkaralinskiy region). Noteworthy, Karkaralinsky is the type locality for The common Eversmann’s hamster prefers semidesert belajevi in Selewin (1934), who further identified Beljaev and dry steppic habitats at low elevations; the range is as the collector of the type specimen. Selewin’s type was between –26 m and 2,020 m (mean = 198 m). obtained on 21 August 1928 and is indeed deposited in Specimens were recorded in various types of virgin ZIN (Baranova & Gromov l. c.). We therefore conclude steppe, a fallow and cultivated land, and Artemisia that both, Argyropulo and Selewin, based their names thickets; they thrive also on fixed sands and saline soils, on the same voucher which makes belajevi Selewin, 1934, providing there is some vegetation cover available an objective synonym of beljaevi Argyropulo, 1933. (Modorov & Polyakov 2021). This hamster penetrates Beljaev (1933) reported A. eversmanni for Central and into the forest steppe however avoids humid Western Kazakhstan, and for Karkaralinsk, but not for environments (margins of woodland belts and Zaysan. depressions). The abundance is significantly higher in grain fields as opposed to pristine steppe (Danini & Distribution. Endemic to southern Russia in Europe Olschwang 1936, Oparin 2005). Occasionally, common and Asia, northern and central Kazakhstan and Eversmann’s hamsters enter buildings (Afanasiev 1953, northern China in Xingjian (Figure 55). The Afanasiev 1960, Shubin 1977d, Shlyakhtin et al. 2009, distribution area is estimated at 1,401,017 km2. The Shenbrot 2017f). western and eastern borders are set sharply by the rivers Volga and Irtysh, respectively. The southern border Characteristics. Dimensions: body mass = 61–93.5 g, tentatively follows the northern shore of the Caspian length of head and body = 136–151 mm, length of tail Sea – northern Aral – central Betpak-Dala Desert – =18–29 mm, length of hind foot = 15–21 mm, length Lake Balkhash; the southernmost record is from the of ear = 13–18 mm, condylobasal length of skull = Baykara Mt. (Jambyl Province, Kazakhstan), while all 27.4–33.6 mm, zygomatic width = 15.3–19.8 mm, the remaining localities lay to the north of the 46th maxillary tooth-row length = 4.0–4.7 mm (Afanasyev parallel. In China, the common Eversmann’s hamster is 1953, Popov 1960, Shubin 1977d); tail is short and restricted to northern Xingjian, where known from the accounts for 17–22% of head and body length (mean = counties of Fuhai, Habahe, and Hoboksar. The 19%; Danini & Olschwang 1936). Fur is short (length northern border is in southern European Russia and = 5.5–6.5 mm) and velvety; scarce black-tipped hairs southern Siberia. All the northward expansions protrude by approximately 2 mm and become more tentatively follow the major rivers reaching the abundant on the rump and around the base of the tail. provinces of north-eastern Ulyanovsk, southern Vibrissae measure 33–35.5 mm. Colour is polymorphic Tatarstan, and southern Bashkortostan (along the (Vorontsov & Krjukova 1969a) and varies from buffy Volga), Omsk and Kurgan (along the Tobol), and the brown to grey-shaded pinkish buff or cinnamon buff. Omsk Province (along the Irtysh). The range segment in eastern Zaysan and adjacent Xingjian is presumably Underside (lips, chin, lower side of mystacial pads, and an isolate. feet) is white with slate hair bases; short hairs on the chin are white to bases. Belly is occasionally dirty-white, During the Late Pleistocene, A. eversmanni expanded its cream-grey, or light grey. Demarcation line is sharp and range westward across the Lower Don River into straight posterior to the arms; on the head, the white Romania and Moldova (Kowalski 2001) and endured SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 85. Figure 56: Allocricetulus eversmanni eversmanni from Saratov, European Russia. Photo courtesy of M. Kabanov underside forms re-entrants below the ear and on the comparatively shorter and longer (≥ 4-times as wide as posterior edge of mystacial pad (Figure 56). Brown long) (Allen 1940, Ross 1992, Gureeva et al. 2020). dorsal pelage extends down the forearm to the wrist and Molars show no peculiarities (Figure 57). is contiguous with the sternal streak between the forelegs (Figure 51). The streak is up to 3–4 cm long Karyotype: 2n=26, NF=38–40; 4 autosomal pairs are but is frequently shorter; it is entirely absent in the east. metacentric of different sizes, 5–6 pairs are Rarely, the streak is medially split into two by white hair. submetacentric or subtelocentric, and 2–3 pairs are Dorsal side of the tail, which is of same colour as the acrocentric. Sex chromosomes are subtelo-, submeta- back, is frequently interspersed by more numerous all- or metacentric; depending on the subspecies, they are black hairs; underside is white. Ears are grey and either isomorphic or heteromorphic (Kartavtseva & darkened towards their tip, with a post-auricular tuft of Vorontsov 1992, Kartavtseva & Surov 2005). whitish or buff hairs. Juveniles are duller than adults. Variation and subspecies. Over the past century, the Glans penis is parallel-sided. It is narrower than in A. number of subspecies recognised in A. eversmanni varied curtatus and also lacks a shallow medial groove on its between 2 (eversmanni and beljaevi; Kuznetsov 1965, ventral side. The central papilla ventralis is smaller than Mitina 1959, Afanasiev 1960, Gromov et al. 1963, papillae laterales; the lateral ones are not expanded Corbet 1978, Shenbrot 2017f) and 3 (microdon, eversmanni terminally. Shaft of the baculum is wider than in A. and beljaevi; Beljaev 1933, Argyropulo 1941a, Ellerman curtatus; greatest width > 80% of shaft’s length as 1941, Vinogradov & Argyropulo 1941, Kuznetzov opposed to < 80% in A. curtatus; the central digit of the 1944, Ellerman & Morrison-Scott 1951, Vinogradov & distal baculum accounts for ¾ of the length of lateral Gromov 1952, Vorontsov & Krjukova 1969a, digit (c. 90% in A. curtatus) (Argyropulo 1933c, Vorontsov 1982). Some of these authors ranked curtatus Vorontsov 1982, Ross 1992). as the palest and the easternmost subspecies of A. eversmanni. Ross (1992), on the other hand, recognized no In comparison to A. curtatus, the skull of A. eversmanni subspecies. has narrower rostrum and palate, more constricted interorbital region (mean width = 4.63 mm), smaller Subspecies were defined according to fur coloration; bullae (average length × width = 5.2 × 5.8 mm), less microdon is the darkest, beljaevi the palest, and the expanded zygomatic arches, longer orbit, nominotypical subspecies is intermediate. The darkest neurocranium, molars, incisive foramina, and diastema, individuals have the most distinct sternal streak and broader incisors (Figure 52). Interparietal is between the forelegs, gradually fading in pale hamsters. 86 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 57: Grinding pattern of upper (a, b, c) and lower (a’, b’, c’) molars in Common Eversmann’s hamster Allocricetulus eversmanni. a, b – Ural River, Kazakhstan, c – eastern Zaysan Basin, Kazakhstan. if2 – internal fold 2, pf2 – primary fold 2. Scale bar = 1 mm. The most detailed subspecific classification was Allocricetulus eversmanni eversmanni provided by Mitina (1959). She distinguished 2 (Brandt, 1859) subspecies, the darker nominotypical which was (chernozem) and the paler Synonym: Mesocricetus microdon Ogneff, 1925 (Mitina beljaevi mapped for northern steppes on black soils from southern dry steppes and semideserts. Vorontsov (1982) concluded 1959); Cr[icetulus] (Allocricetulus) eversmanni beljaevi that colour is adaptive and depends on a small-scale Argyropulo, 1933. steppe–desert mosaic; despite this, he still recognized 3 subspecies, claiming that differences between them are Taxonomy. The nominal subspecies is further sub- clearly seen in series. Lebedev (2012) stressed, however, structured in 3 phylogeographic lineages, which supposedly separated 67–79 kya (CI = 28–142 kya). that subspecific taxonomy does not correspond to the One lineage is widespread and further 2 lineages are observed pattern of phylogeographic variation. restricted to northern Kazakhstan and south-eastern The most divergent lineage of Kazakhstan, respectively. The most distinct lineage A. eversmanni occupies occupies western East Kazakhstan and eastern the extreme eastern portion of the species’ range in the Qaraghandy. Denser sampling is needed, however, to Zaysan Basin (eastern Kazakhstan), displaying a properly understand the geographic scope of these confusing mixture of the curtatus -type external lineages (Gureeva 2022). morphology (greyish-buff dorsal pelage and no sternal strike) and the eversmanni-type of karyotype (Vorontsov & Krjukova 1969a). This population is frequently Distribution. The entire range of the species except for referred to as Zaysan Depression in eastern Kazakhstan and the pseudocurtatus and does not include beljaevi . north-western part of Dzungarian Basin in China. The Zaysan hamsters were at first diagnosed by karyotype (Kartavtseva & Vorontsov 1992) and subsequently by mitochondrial markers (Gureeva Characteristics. Autosomes: 5 pairs are telocentric + 2022). Based on molecular clock, Gureeva (2022) 3 pairs are acrocentric elements (in addition to 4 pairs of metacentrics). Sex chromosomes are isomorphic and estimated divergence between the Zaysan hamsters submetacentric; fundamental number of chromosomal from the remaining A. eversmanni at 102 kya (CI = 50– arms NF = 40 (Kartavtseva & Vorontsov 1992, 212 kya), which postdates the divergence between A. Kartavtseva & Surov 2005). Fur colouration is highly eversmanni and A. curtatus (~ 120 kya) for merely 18 ka; variable; the sternal streak is present though pairwise genetic (K2P) distances are 2.0 (Zaysan– occasionally inconspicuous and sometimes split eversmanni s. str. ) and 2.3 (Zaysan– curtatus ). medially into 2. The overall skull shape is on average SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 87. more similar to A. curtatus than is A. e. pseudocurtatus combination of the external appearance of Allocricetulus (Gureeva et al. 2020). curtatus and the karyotype of A. eversmanni. The darkest hamsters, which were occasionally Taxonomy. The majority of authors followed Mitina classified in the past as a subspecies microdon, occur (1959) and labelled all pale A. eversmanni occurring to between the Volga and Ural Rivers and in the Ural Mts. the south of the 55th parallel as beljaevi. More rarely was Dorsal fur is tawny-olive, hairs have long dark terminal beljaevi restricted to Zaysan (Kuznetzov 1944, band, and the sternal streak is distinct and long; ventral Vinogradov & Gromov 1952, Afanasiev 1953, 1960). hairs have long and dull grey basal band. Hamsters The Zaysan population was also named pseudocurtatus occupying the black soils eastward of the Ural Mts. and (Kartavtseva & Surov 2005, Romanenko et al. 2013, northward of the 55th parallel have bright sayal-brown Gureeva 2022) or was treated as transitional between A. back, a comparatively long dark bands on dorsal hairs e. eversmanni and A. e. curtatus (Kuznetsov 1932). The and distinct sternal streak, which is in some individuals entire isolate in Zaysan shows footprints of medially split into 2. These animals were classified as mitochondrial introgression from two phylogenetic the nominotypical subspecies and were occasionally lineages of A. eversmanni s. str. occupying Kazakhstan. referred to as of intermediate colouration. The transition between the darkest and the intermediate Distribution. Restricted to the Zaysan Basin in eastern populations was reported for the Orenburg region Kazakhstan and north-western China. (south European Russia; Kuznetsov 1932). Hamsters living to the south of the 55th parallel are the lightest Characteristics. Autosomes: 6 pairs are telocentric + and were in the past usually classified as subspecies 2 pairs are acrocentric (in addition to 4 pairs of beljaevi. They are dorsally light fawn grey to wood- metacentrics). Sex chromosomes are heteromorphic; brown, with distinct buffy and grey tint; dorsal hairs the Y chromosome is submeta- or subtelocentric and is have short dark terminal bands. The sternal streak is smaller than the meta- or submetacentric X inconspicuously light-fawn, and frequently split in 2. chromosome; fundamental number of chromosomal Ventral hairs have the shortest and palest grey basal arms NF = 38 (Kartavtseva & Vorontsov 1992, band (Kuznetsov 1932, Mitina 1959, Vorontsov & Kartavtseva & Surov 2005). Colouration is as in pale Krjukova 1969a). The palest hamsters occupy sands of individuals of the nominal subspecies. Dorsal side is Aral (Mitina 1959). Transition between the intermediate pinkish cinnamon to cinnamon buff with admixture of and pale hamsters was reported from Naruzum and grey; dorsal hairs have short dark terminal band. The Semiozernoe in the Qostanay Region (north sternal streak is inconspicuous light-fawn and Kazakhstan; Mitina 1959). frequently split in 2; hamsters occupying Aygyr-Kum and the Dala sandy desert (eastern Zaysan Basin) have There is little morphological variation among no sternal stripe and are externally indistinguishable populations besides colouration. In Kazakhstan, from A. curtatus (Vorontsov & Krjukova 1969a). hamsters living in the south display larger size and more Ventral hairs have short pale-grey basal band. pronounced secondary sex dimorphism (Shubin 1977d). Allocricetulus curtatus (Allen, 1925) – Mongolian Eversmann’s hamster Allocricetulus eversmanni pseudocurtatus Kartavtseva & Cricetulus migratorius curtatus G. Allen, 1925: 3. Type Vorontsov, 1992 locality: “Iren Dabasu [Ehrlien], Mongolia”; subsequently emended to “Inner Mongolia” (Allen Etymology. 1940: 764), China. The name is composed of ‘pseudos’ Formozov, 1929: 50. Name Cricetulus curtatus: (Greek for ‘false’) and curtatus , which is the species combination and rank change. epithet for Mongolian Eversmann’s hamster. The name Cr[icetulus] ev[ersmanni] curtatus: Kuznetsov, 1932: 95. (false Mongolian Eversmann’s hamster) is allusion to a Name combination. 88 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Cr[icetulus] (Allocricetulus) curtatus: Argyropulo, 1933b: Distribution. The entire range covers 766 thousand 245. Name combination. km2. The core distribution covers Mongolia and central A[llocricetulus] curtatus: Vinogradov & Argyropulo, 1941: Nei Mongol (China), reaching the southernmost Tuva 169. First use of the current name combination. (Tyva; Russian Federation) in the north and northern China in the south: eastern Gansu, Ningxia, eastern Etymology. Species name curtatus (masculine) is Latin Xinjiang (as far west as Yiwu and Mori), and marginally for ‘short-tailed’, in allusion to the short tail of the Hebei. Several Chinese records transgress the Ordos species. While naming this taxon, Allen believed that A. loop and occur on the right bank of the Huang He curtatus is a subspecies of Nothocricetulus migratorius with River (Figure 58). Mongolian range, which closely apparently shorter tail. coincides with the biome of desert and xeric shrubland (Olson et al. 2001), extends from the Uvs Nuur Basin Taxonomy. Originally described as a subspecies of in the north-west further southward and eastward. In Nothocricetulus migratorius (Allen 1925); subsequently its western part, the range is squeezed between the classified as a subspecies of A. eversmanni (Allen 1940, Khangai Mts. from the north, Mongol Altai from the Kuzntzov 1944, Mitina 1959, Kuznetsov 1932, 1965, west, and Gobi Altai from the south. Further east, the Ellerman & Morrison-Scott 1951, Ma et al. 1987, Zhang northern range border is set by temperate grasslands et al. 1997, Luo et al. 2000) or a species in its own right reaching the western Sühbaatar Province. Mongolian (Argyropulo 1933b, c, Ellerman 1941, Vinogradov & hamster occupies gravel semideserts, saline soils and Argyropulo 1941, Flint 1966b, Stubbe & Chotolchu fixed sands with geophytes, cereals, halophytes, 1968, Corbet 1978, Corbet & Hill 1980, 1986, Gromov shrubland and cereal cultivations (Bannikov 1954, & Erbajeva 1995, Musser & Carleton 1993, Pavlinov & Chugunov 1962, Sokolov & Orlov 1980, Fu et al. 2005). Rossolimo 1987, Wang 2003, Musser & Carleton 2005, Elevational range is 750–2,455 (mean = 1,330 m). Lebedev et al. 2016, Shenbrot 2017g). For further details, see the account on Taxonomy and Characteristics. Slightly smaller than A. eversmanni but nomenclature under A. eversmanni (above). of identical body proportions (Figures 51 & 59). Figure 58: Distributional range of the Mongolian Eversmann’s hamster Allocricetulus curtatus. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 89. Figure 59: Mongolian Evresmann’s hamster Allocricetulus curtatus from Republic of Tyva, Russian Federation. Photo courtesy of M. Kabanov Dimensions: body mass = 35–70 g, length of head and When viewed from above, the glans penis is barrel- body = 112–146 mm, length of tail = 14–27 mm, length shaped; it is comparatively wider than in A. eversmanni of hind foot = 14–20 mm, length of ear = 13–19 mm, and has a shallow medial groove. Papillae ventrales are of condylobasal length of skull = 26.6–31.6 mm, approximately same size; the 2 papillae laterales have zygomatic width = 15.0–19.0 mm, maxillary tooth-row lateral expansion that gives a Г-shaped appearance. length = 4.0–4.9 mm (Bannikov 1954, Luo et al. 2000); Shaft of the baculum is less expanded than in A. tail accounts for 14–22% of head and body length eversmanni; the greatest width < 80% of shaft’s length; (mean = 19%). Fur is softer and longer than in A. the central digit of distal baculum accounts for eversmanni (length = 7–10.5 mm); scarce black-tipped approximately 90% of length of lateral digits hairs protrude for ~ 1–3.5 mm. Vibrissae measure up (Argyropulo 1933c, Vorontsov 1982, Ross 1992). to 27–37 mm. Tail is densely haired; hairs at its base are longer and produce a rather conical appearance (Figure 51); terminal pencil is ~ 3.5 mm long. Dorsal fur is pale buff to cinnamon buff and evenly lined with black- tipped hairs; some individuals show brown streak across shoulders posterior to the cheek-pouch. Underside (lips, chin, the lower portion of mystacial pads, and feet) is white with slate-grey bases; hairs on the chin, throat and sometimes between the fore legs are white to bases. Demarcation is less sharp than in A. eversmanni. Sternal streak is absent in the great majority of animals; occasionally, light-fulvous to rusty hairs, or more extensive grey hair bases form a just noticeable patch on the throat. Tail is white all-round, sometimes with darker medial stripe; feet are white. Ears are of same shade as the back and thinly clad by short whitish and dusky brown hairs; there is an extensive post- Grinding pattern of upper (a) and lower (a’) molars in Figure 60: auricular tuft of whitish hairs. Juveniles are greyish- Mongolian Eversmann’s hamster Allocricetulus curtatus from brown. Mongolia. if 2 – internal fold 2, pf 2 – primary fold 2. Scale bar = 1 mm. 90 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. The skull (Figure 52) has more massive rostrum and pre-Linnean authors, including Gesner (1602), Topsel wider palate than in A. eversmanni; the interorbital region (1658) and Ray (1693) (reviewed in Buhle 1821). Leske is wider (mean width = 5.05 mm), and zygomatic arches (1779) established the genus Cricetus for 3 rodents which are more expanded; bullae are more swollen (average possess internal pouches: Mus cricetus of Linnaeus and 2 length × width = 5.56 × 6.19 mm), the orbit, ground squirrels (Spermophilus and Marmota). At about neurocranium, molars, incisive foramina, and diastema same time, Zimmermann (1777) used the name Cricetus are shorter, and incisors are narrower. Interparietal is exclusively for the common hamster, although not as a comparatively shorter (< 4-times as wide as long) (Ross binomial name. Towards the end of the 18th century, 1992, Gureeva et al. 2020). Molar pattern shows no Cricetus was usually understood to contain true hamsters peculiarities (Figure 60). (current Cricetinae), i. e. the Linnean cricetus and taxa named by Pallas (1773, 1779), which are now in Karyotype: 2n=20, NF=38; 5 autosomal pairs are Cricetulus, Nothocricetulus, and Cricetiscus. Rodents other metacentric of different sizes, 3 pairs are than hamsters were exceptionally also classified as submetacentric and subtelocentric, and 1 pair is Cricetus, e. g. Chinchilla (Geoffroy 1803) and Hesperomys s. acrocentric. Sex chromosomes are medium sized lat. (Flower & Lyddeker 1891, Thomas 1888). On the submetacentrics, which are heteromorphic with respect other hand, a broad definition of Cricetus (with the to the position of the centromere (Orlov et al. 1978). inclusion of Cricetulus s. lat. and Mesocricetus as subgenera) still prevailed at the start of the 20th century (e. g. Winge Variation and subspecies. Phylogenetic analysis 1887, Trouessart 1904). Following the generic based on mt markers retrieved 2 weakly divergent segregation of Cricetulus and Mesocricetus (Satunin 1900, (divergence ≈ 1%) allopatric lineages with a contact at Trouessart 1910, Miller 1912), Cricetus was nearly the Valley of the Lakes and the Gobi Altai Mts. universally understood as a monospecific taxon (Gureeva 2022). Mongolian Eversmann’s hamsters (Vinogradov 1933b, c, Ellerman 1941, Kuznetzov tend to be paler along the southern distribution edge 1944, Vorontsov 1958, and subsequent authors). The (Chugunov 1962). Despite all this, the species is only noteworthy deviation was the incorporation into classified as being monotypic (Shenbrot 2017g). Cricetus of Mesocricetus (Argyropulo 1933b, c, 1941a, Kuznetsov 1965), or Allocricetulus (Stroganova 1954, GENUS: Cricetus Leske, 1779 – Popov 1960) or of both (Vinogradov & Gromov 1952, Common Hamsters 1956). Cricetus Zimmermann, 1777: 343. Not used as Linnean morphology (Figure 67) clearly separates Although the external (Figure 61) and cranial Cricetus Palmer 1904: 203, Kryštufek et al. 2020: 10). within Cricetinae. Different phylogenetic Leske, 1779: 168. Type species is Mus cricetus reconstructions therefore yielded conflicting results on Linnaeus, 1758, by tautonomy. intergeneric relationships ( binominal, hence invalid (Nehring 1898c: 493, other hamsters, it obscures its phylogenetic position Cricetus from Heliomys nigricans Lacépède, 1799, by monotypy. proximity of Cricetus with Mesocricetus. This view was Gray, 1873: 417. Type species is Heliomys jeudei already suggested by Argyropulo (1933b, c) who Gray, 1873 (= Mus cricetus Linnaeus, 1758), by stressed a colourful pelage and a ridged skull in both Hamster Lacépède, 1799: 10. Type species is Hamster attempts (Ross 1992, Potapova 2005) suggested close cf. Figure 1). Two of these Hellomys monotypy. genera. Fahlbusch (1969) speculated that Cricetus : Shubin, 1977c: 249. Incorrect subsequent diverged from Cricetulus + Phodopus lineage during the spelling of Heliomys Gray. Miocene. Chromosomal (Romanenko et al. 2007) and Taxonomy. The common hamster of Germany was 2020), however, safely placed molecular evidence (Lebedev et al. 2018a, Ding et al. named (as ‘Cricetus’ or ‘hamester Germanicae’) and as is defined here, and close to Cricetus inside Cricetina, briefly described already by Albertus Magnus (c. 1200– comparison between Allocricetulus. For 1280) in his 2 treatise on quadrupeds (pp. 1374–1375 nd Allocricetulus and Cricetus, see generic account of the former. in Stadler 1920) and was frequently referred to by the SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 91. The extant common hamster populations are uniformly depending on the authority (reviewed in Kryštufek et al. classified as monospecific. In the past, Cricetus was only 2020). exceptionally split taxonomically; e. g. Matschie (1901) recognized 4 allopatric species (cricetus, canescens, rufescens, Etymology. The name Cricetus was used as early as in nehringi). Taxonomic scope of fossil hamsters is more the 13th century by Albertus Magnus (Weissenborn ambiguous on both the generic and the species levels. 1839). It originates from Italian ‘criceto’ for hamster Cricetus is hypothesized to originate anywhere between (Palmer 1904) and presumably originates from Greek the middle Miocene and early Pleistocene, and the κ ϱιξω meaning ‘I scream’ (Weissenborn l. c.). Ross extant C. cricetus supposedly evolved between the late (1992: 287) suggested that Cricetus “was probably Pliocene–early Pleistocene and the late Pleistocene, derived from the Illyrian ‘skrzeczieck’ (Gesner 1602), Figure 61: Common hamster Cricetus cricetus from Austria. Photo courtesy of Frank Zachos 92 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. and refers to the cheek-pouches which characterize the Gebiete [= in Thuringia (Germany), as well as in the hamsters.” The tag ‘Illyrian’, although frequently area of the Ural Mts. (Russian Federation)].” quoted in the pre-Linaean literature (cf. Topsel 1658), is M[us] C[ricetus] albus Bechstein, 1801: 1009–1010. Type perhaps misleading in this context (Kryštufek & locality is “in Thüringen, so wie im Uralischen Pozdnyakov 2018: 217). ‘Skrzeczieck’, however, is Gebiete [=in Thuringia (Germany), as well as in the undoubtedly of Slavic origin being in use, historically, area of the Ural Mts. (Russian Federation)].” currently, or both, in Polish (Skreczecz, Skrezéczek), M[us] C[ricetus] fulvus Bechstein, 1801: 1010. Type Czech (Sskrecek, Skřeček, Křeček, Křeč) and Slovak locality is “Thuringia”, Germany. (Skrečok, Škrček, Skreček, and Škrečok). Its derivatives Cricetus vulgaris Geoffroy, 1803: 196. Type locality is ‘křeček’, ‘hrček’, ‘hârciogul’ etc. predominate in 5 “L’Europe septentrionale et orientale [= northern linguistic groups in the Pannonian and Carpathian and eastern Europe].” Basins of Central Europe and are presumably Cricetus frumentarius Pallas, 1811: 161. New name for Mus onomatopoeia, imitating the hamster’s vocalization cricetus Linnaeus, 1758 (Miller 1912: 602), ‘khr’ and ‘gr’ (Kryštufek & Pozdnyakov 2018). Nehring presumably to avoid tautonymous combination (1898c) explained Cricetus as “a medieval Latinization of Cricetus cricetus (Kryštufek et al. 2020: 11). the vulgar name Krietsch”. Cricetus fuscatus Brandt, 1835: 435. Not 1832 (Ross 1992: 291). Geographic origin not known. A member of Cricetus cricetus (Linnaeus, 1758) – Cricetus (cf. Trouessart 1910: 160), though regarded Common Hamster as unidentifiable by Ellerman & Morrison-Scott (1951: 625) and Pavlinov & Rossolimo (1987: 174). [Mus] cricetus Linnaeus, 1758: 60. Type locality is “Eur. Österreich, Böhmen, Mähren, Ungarn, [Cricetus vulgaris] varius Fitzinger, 1867: 98. Type locality “Germania [Germany]”, with reference to Ray was restricted to “Thüringen [Thuringia]” (Thomas Fitzinger, 1867: 98. Type locality [Cricetus vulgaris] albus 1911: 147), following Ray ( l. c. ) who reported C. is “Eur. Deutschland [Europe. Germany].” cricetus for “Turingia & Miſnia [Miśnia = Miessen, Homonym of (1693: 221) and Gesner (1602: 738). Type locality Hungary, Germany].” Deutschland [Europe. Austria, Bohemia, Moravia, Saxony]”. Fitzinger, 1867: 98. Type locality albus Bechstein, 1801. M[us] Cricetus germanicus Kerr, 1792: 243. Type locality Sibirien, Simbirsk, Usa [Europe. Austria, Hungary, “Germany.” Germany. – Asia. Siberia, Simbirsk (= now M[us] Cricetus german[icus] niger Kerr, 1792: 243. Type Ulyanovsk), Usa (either the Usa River, which is the Glis cricetus: Erxleben 1777: 363. Name combination is “Eur. Österreich, Ungarn, Deutschland. – As. [Cricetus vulgaris] niger locality “Siberia, the south of Russia, Poland, Mus Cricetus niger beyond the Rhine, especially in Thuringia.” the lower reaches of the Usa].” Homonym of niger Schreber, 1792: Plate CXCVIII B. Kerr, 1792. Without type locality. Homonym of niger Kerr, 1792, Cricetus frumentarius niger Sclavonia, Hungary, Silesia, Bohemia, and Germany Oblast’, or the settlement Usa, now Usinskoye, in right tributary of the Volga River in the Samara however, we could not ascertain which of these locality is “ Bogdanov, 1871: 171. Type names holds priority. Russian Federation. Homonym of въ Казан. губ. [in Kazan Governorate],” Hamster nigricans Lacépède, 1799: 10. Type locality Heliomys jeudei niger Kerr, 1792. Cricetus Germanicus: Morrison-Scott (1951: 628). : Dahl, 1894: 130. First use of the current Cricetus cricetus Leske, 1779: 506. Name name combination. combination. Cricetus vulgaris unknown; stated as “Germany” by Ellerman and known. Gray, 1873: 418. Type locality is not M[us] combination. [Belgium, from the left bank of the Maas River];” C[ricetus] variegatus Bechstein, 1801: 1009. Type restricted to “Near Fexhe-Slins, banks of the Maas, locality is “in Thüringen, so wie im Uralischen Belgium” (Miller 1912: 603). Cricetus german[icus] niger: Leske, 1779: 506. Name locality is “Belgien, vom linken Ufer des Maas var. canescens Nehring, 1899b: 1. Type SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 93. Cricetus vulgaris var. rufescens Nehring, 1899b: 2. Type Cricetus vulgaris stavropolicus Satunin, 1907: 122. Type locality is “bei Tjubuk im dem Ural-Gebiete [near locality: “Сел. Предтеча, Ставропольской Tjubuk in the area of Ural],” Chelyabinsk Oblast, губернiи;” (Russian version), “Dorf Predteča, Kasli Rayon (Pavlinov & Rossolimo 1987: 173), Gouv. Stavropol [= Village Predtecha, Governorate Russian Federation. Stavropol]” (German summary on p. 162), Cricetus nehringi Matschie, 1901: 232. Syntypes were from Stavropol Krai, Russian Federation. “Slobosia, Cernavoda und Barza [Slobozia, Cricetus vulgaris stawropolicus: Satunin, 1908: 11. Incorrect Cernavodă and Barzâ];” Miller (1912: 605) restricted subsequent spelling of stavropolicus Satunin, 1907. type locality to “Slobosia [Slobozia]”, Ialomiţa Cricetus vulgaris stauropolicus: Lydekker 1909: 64. Incorrect County, Romania. subsequent spelling of stavropolicus Satunin, 1907. Cricetus vulgaris babylonius Nehring, 1903: 360. Type Cricetus cricetus niger: Trouessart, 1910: 394. Name locality, which is given as “südöstlich von Bagdad combination. Trouessart referred to niger of several [southeast of Baghdad]”, is evidently erroneous authors; the only identifiable combination is niger considering that the common hamster does not Simroth, 1906. occur in the Middle East (cf. Figure 62). Nehring Cricetus cricetus stavropolicus: Trouessart, 1910: 395. Name purchased the type voucher from a certain Schlüter, combination. a dealer in natural history objects, who had obtained Heliomys jeudii: Miller, 1912: 602. Unjustified it from his supplier from “Babylonia”. Wepner emendation of jeudei Gray, 1873 (Kryštufek et al. (1934: 438) suggested that Nehring’s voucher 2020: 11). originated from the Caucasus, and not from the Cricetus frumentarius polychroma Krulikovsky, 1915: 6. Tigris River. In Wepner’s view, the locality was Replacement name for Cricetus frumentarius niger perhaps “Bagdat südöstlich von Kuteis in den Bogdanov, 1871. südlichen Ausläufern des Kaukasus” [Bagdati near Cricetus cricetus latycranius Ognev, 1922: 110. Type locality Kutaisi in Georgia]; C. cricetus, however, does neither is “Николаевcкий у. Самарской губ., Черемушка occur in Georgia or elsewhere to the south of the [Nikolaevskiy uezd, Samara Governorate, Caucasus. Wepner further speculated that the Cheremushka],” now Samara Oblast, Russian collector could possibly be from Kutasi, while the Federation. hamster was actually captured in “Gebiet nördlich Cr[ricetus] cr[ricetus] rufescens: Ognev, 1922: 111. Name des Kaukasus [the area north of the Caucasus].” She combination. concluded that “It seems certain that babylonicus (sic) Cr[ricetus] cr[ricetus] stawropolicus: Ognev, 1922: 111. designates the Caucasian hamster” (“Jedenfalls aber Name combination and incorrect subsequent scheint sicher, daß der Name habylonicus (sic) den spelling of stavropolicus Satunin, 1907. Kaukasushamster bezeichn”) and therefore predates Cricetus c[ricetus] tauricus Ognev, 1924: 19. Type locality stavropolicus Ognev. is “окрестности Симферополя [= vicinity of [Cricetus cricetus] canescens: Trouessart, 1904: 394. Name Simferopol],” Crimea, Ukraine. combination. Cricetus c[ricetus] tomeniss Ognev, 1924: 19. Type locality [Cricetus cricetus] rufescens: Trouessart, 1904: 394. Name is “дер. Круглихина, Томской губ. около г. combination. Томска [= village Kruglikhina, Tomsk [Cricetus cricetus] nehringi: Trouessart, 1904: 394. Name Governorate, vicinity of the city of Tomsk],” Tomsk combination and new rank. Oblast, Russian Federation. Incorrect spelling of [Cricetus cricetus] babylonicus: Trouessart, 1904: 394. Name tomensis Ognev, 1924. combination and emendation of babylonius Nehring, Cricetus c[ricetus] tomensis: Ognev, 1924: Table V on p. 21. 1903. Correct spelling of tomeniss Ognev, 1924. Cricetus vulgaris niger Simroth, 1906: 337. Type locality Cricetus cricetus nehringii: Călinescu, 1931b: 34. Incorrect was not given; Miller (1912: 602) reported it as subsequent spelling of nehringi Matschie, 1901. “Saaltale [=Valley of the Saale, Germany]”. Cricetus cricetus fuscidorcis Argyropulo, 1933a: 235. Correct Homonym of niger Kerr, 1792. spelling is fuscidorsis (see p. 236). Type locality is “окр. с. Ново-Антоновского, Черкасской вол., 94 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Лепсинского у., Джетысуйской губ. northern Croatia and northern Serbia (Ružić 1978), [=neighbourhood of the village of Novo- southern and central Poland (Surdacki 1983), southern Antonovsky, Cherkasy volost, Lepsinsky uyezd, Belarus (Serzhanin 1961, Lemyanchik 2006), Ukraine Dzhetysu province].” An abbreviated transliteration (Mezhzherin & Lashkova 2013), Romania (Murariu in Argyropulo (1933a: 235) reads: “Novo 1998), Moldova (Lozan 1971), northern Bulgaria Antonovskoje, Distr[ict] Lepsinsk, Semiretshje (Popov 2007), Russian Federation (Berdyugin & [Semirechye, now Zhetysu],” Almaty Province, Bolshakov 1998), northern Kazakhstan (Shubin 1977c), Kazakhstan. The year of publication is frequently and extreme northwestern Xinjiang in China (Zhang et stated as 1932 (Ellerman 1941: 440, Ellerman & al. 1997). Report for Luxemburg (Saint-Girons 1973: Morrison-Scott 1951: 629); for 1933 see Argyropulo Figure 91) is obviously erroneous (Schley & Herr 2018). (1933b: 243) and comments in the account on Allocricetulus. Pavlinov & Rossolimo (1987: 173) The entire range covered an estimated 2,370,500 km2. condemned ‘fuscidorsis Argyropulo, 1932: 243 The western border is on the left bank of the River [actually Argyropulo, 1933a]’ nomen nudum due to Rheine, and the eastern border on the right bank of the lack of description. They seemingly referred to Yenisei River, the western ends of the Minussinsk Argyropulo’s revision of Cricetinae (Argiropulo Steppe and the edges of Betpak-Dala Desert (Shubin 1933b), which is indeed without a description, but 1977c). In the northwest, the range closely approaches overlooked the Argyropulo’s (1933a) article in the Atlantic and North Sea coasts; further east in which Poland, the border sharply turns south and follows the fuscidorsis was properly diagnosed. Cricetus cricetus polychroma: Ellerman, 1941: 440. Name line Brest–Rovno–Gomel’–Smolensk–Rzhev–Yaros- combination. lavl’–Vyatka–Perm–Ekaterinburg–Tjumen–Tobol’sk– C[ricetus] polychromata: Popov 1960: 323. Incorrect Kolpashevo–Krasnojarsk (Berdyugin & Bolshakov subsequent spelling of polychroma Krulikovsky, 1915. 1998, Sidorov et al. 2009). The southern border is C[ricetus] c[ricetus] laticranius: Gromov, 1963: 497; in roughly set by the Alps, the River Danube and its Gromov et al. (1963). Incorrect subsequent spelling southern tributary the Drava (Niethammer 1982), the of latycranius Ognev, 1924. Black Sea coast and the Caucasus (Tembotov 1972). C[ricetus] c[ricetus] latieranius: Gromov, 1963: 497; in Further east, the range border runs to the north of the Gromov et al. (1963). Incorrect subsequent spelling Caspian coast but descends south along the Ural River of laticranius Ognev. and reaches the estuary of the Emba River into the Hellomys sendii: Shubin, 1977c: 249. Incorrect Caspian Sea. From the northeastern corner of the subsequent spelling of Heliomys jeudei Gray. Caspian, the range roughly follows the line to the north C[ricetus] c[ricetus] pannonicus Neumann, 2013: 13. of the Aral Sea–Balkhash Sea, encompasses Semirechye Nomen nudum. (Shnitnikov 1936) and reaches Dzungarian Alatau and the extreme northwestern Xinjiang (Kuznetsov 1965, Distribution of C. cricetus (Figure 62) covers a wide belt Shubin 1977c, Zhang et al. 1997). extending longitudinally for 5,500 km from northwestern and Central Europe, across Russia and The abundance of the common hamster and the Kazakhstan, as far east as the River Yenisei and expansion of its range varied over the last centuries to Xinjiang (Niethammer 1982, Kryštufek et al. 2020). a degree far greater than in any other hamster. Range During the 20th dynamic was seemingly not synchronous across the century, when the range was at its largest, the species occupied eastern Belgium (Libois & entire range. In short, common hamsters benefited Rosoux 1982), eastern France (Louarn & Saint Girons from deforestation and land use change for agriculture 1977), southern Netherlands (Saint-Girons 1973), (Grulich 1978), however, industrialization in food Germany (Meinig et al. 2014), Switzerland (vouchers in production drastically affected the carrying capacity of NHMBa), Czech Republic (And their habitat and precipitated sharp decline. In ĕ ra & Gaisler 2019), northeastern Austria (Spitzenberger & Bauer 2001), Germany, abundances were locally high in the late 17th Slovakia (Krištofík and Danko 2012), Hungary (Zoltán century at the latest (Weissenborn 1839); the species 2007), northeastern Slovenia (Kryštufek 1991), remained abundant throughout the 18th century and SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 95. .s etu ric s c tu ice Cr er st am h on m m he co f t ge o an l r na io ut rib ist D re 62: gu Fi 96 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. continued spreading its range during the 19th century (Nechay 2000) and at about same time the animal was (Nehring 1894a). A major expansion in the west started still classified as “a significant pest” in central and during the 2nd half of the 19th century. From Belgium, eastern Europe (Nechay et al. 2000). Population where hamsters were still uncommon prior to 1850 recovery was noted in Crimea since the mid-1980s (Sélys 1842), they expanded after 1870 into France (Evstafiev 2016) and in some parts of European Russia (Trouessart 1910) and Holland (Lenders & Pelzers in the 1990s (Poplavskaya et al. 2016). Despite all this, 1985). The species reached pest proportions in the the overall recent trend was a decline, which was 1880s, spread to the outskirts of Brussels in 1930–1940s particularly rapid in the west. In Central and Western and stretched its range to the maximum around 1950 Europe, >75% of the original range has been lost (Bont 2021). In southern provinces of European (Surov et al. 2016). What is left is heavily fragmented Russia, hamsters were “moderately frequent” at the (cf. Figure 2 in Meinig et al. 2014) and marginal turn of the 18th–19th centuries (Rumyantsev et al. 2018). populations (in Switzerland, Holland and Slovenia) Other reports corroborate hamster’s rarity in various have already vanished. In Asia, the decline was less regions of Russia and Kazakhstan during the 19th severe than in Europe (Moskvitina et al. 2022). century (Berdyugin & Bolshakov 1998). In the steppes of Ciscaucasia, where hamsters were always rare Original habitats are perennial grasslands and forest (Tembotov 1960, 1972), they invaded Kabardino- steppes on thick soil layer, however, hamsters promptly Balkaria shortly before 1900 (Satunin 1901). adapted to cultivated areas where they attained the Abundances increased in the late 1920s and during highest abundances. They occupy various open habitats 1930s in many parts of Russia (Viktorov & Istomin as well, like orchards, thickets, and forest edges, but are 2002, Rusinov 2004, Bobrov et al. 2008) and during the largely absent from dry steppe. In eastern Europe, the 1940s in Kazakhstan (Berdyugin & Bolshakov 1998). Urals and the mountains of Asia (Tarbagatai, Hamsters reached the city of Moscow around 1970 Dzungarian Alatau, Altai, and Sayan), hamsters (Sudeikin et al. 1972) and the easternmost Minussinsk occasionally occupy open deciduous and mixed Basin in the 2nd half of the 20th century (Gromov & woodland (Kulik 1962, Berdyugin & Bolshakov 1998). Erbajeva 1995). In Semirechye, first hamsters were Hamsters are primarily inhabitants of low elevations. recorded in Dzungarian Alatau in 1910 and some 3 Mean altitude is 232 m a.s.l. and in Central Europe decades afterwards they occupied also the Balkhash- hamsters mainly remain at <500 m a. s. l. (Kryštufek et Alakol Depression (Afanasiev 1953). Southern Altai al. 2020). They ascend into higher altitudes along the was colonized after the advent of soil ploughing southern range border, i. e. up to 1,150 m in the (Kuznetsov 1932); e. g. hamsters were observed in the Caucasus (Tembotov 1972) and up to 2,000–2,200 m in area of Lake Teletskoye in the mid-1930s (Jurgenson Dzungarian Alatau (Shubin 1977c). 1938). C. cricetus has for long been known to occupy urban Population decline was recorded throughout the 20th settlements (Bogdanov 1871), however, the process of century in various parts of hamster’s range (cf. synurbanization accelerated in the early 20th century Berdyugin & Bolshakov 1998, Nechay 2000). In The (Serebrennikov 1929, Afanasiev 1953). Hamsters are Netherlands, hamsters reached pest abundance merely now present in cities from Prague and Vienna in the a decade since their first appearance in the 1870s, but west to Novosibirsk and Omsk in the east. In many population plagues ceased already after 1915 (Lenders regions, hamsters are known primarily as synanthropic & Pelzers 1985). Population decline was noted since the animals (Poplavskaya et al. 2016); in Crimea, common 1950s in Russia and the Altai (Minoransky et al. 1997, hamsters occur inside the buildings with house mice Oparin 2005, Stakheev 2008). Contrary to this, Sutcliffe and brown rats (Evstafiev 2016). Triggers towards & Kowalski (1976: 85) concluded that hamsters were synanthropisation are contested. While Grulich (1978) “gradually increasing expansion” in West Europe still in observed a switch towards synanthropy during the the 1970s. At about same time (1972), eastern Slovakia population outbreak, Evstafiev (2015) considers the marked a sudden major outbreak (Grulich 1978). phenomenon to be related to population decline. France continued to control hamsters as late as 1990 SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 97. Characteristics. Cricetus is the largest extant hamster of frequencies (e. g. <0.01% in Central Germany; Keyser a robust and heavy-set form (Figure 61). Dimensions: & Stubbe 2000). Colour polymorphism is further body mass = 146–860 g, length of head and body = detailed in the Variation and subspecies section. 165–320 g, length of tail = 28–68 mm, length of hind foot = 26.0–46.0 mm, length of ear = 17.0–41.0 mm, condylobasal length of skull = 36.8–58.9 mm, zygomatic width = 20.5–34.7 mm, maxillary tooth-row length = 6.6–8.9 mm (Grulich 1987a). Secondary sex dimorphism in size is pronounced (Figure 67); in Central Europe, males are on average by 31–44.6% heavier than females, but this differs among populations. Males have by 3.7–14% longer head and body, and by 1.56–7% longer skull (Grulich 1987b). Moving eastward, the secondary sex dimorphism is diminishing (Kryštufek et al. 2016); e. g. dimensions, which Shubin (1977c) published from Kazakhstan, suggest no significant dimorphism in body mass. Length of tail accounts for 22–25% of head and body length (mean = 23%). Head is heavy and powerful, with comparatively small eyes. Ears are long and circular, densely clothed on both sides with fine hairs. Feet are Figure 63: Standard museum skin of Cricetus cricetus (from western broad and fingers are comparatively the longest in the Siberia) in dorsal (top), lateral (middle) and ventral view (bottom). subtribe Cricetina (Figure 33d); the central digit (digit Light patches: I – cheek, II – neck, III – axillary, IV – thigh; c. – III) is the longest in both, the front and hind feet. The antebrachial cuff; c.s. – chin streak; f.g. – flank gland. front thumb is reduced but still prominent and The tricolour pelage is brownish buff across much of equipped with a fairly large nail. Claws are usually thick the back, but is rusty on the head, muzzle and broader on the front paw. There are 5 plantar and 6 frequently also on the rump. The dorsum is clouded by and prominent, more elongate on the hind foot and sprinkling of black-tipped hairs. Flanks are lightly palmar pads. The former are of unequal size; the medial tinged reddish and the belly is uniformly black; the anal and the central interdigital pads are small, while the region and the tail are rusty. There are 4 contrasting Plantar pads are of small size; the medial interdigital pad light patches along the side, specifically (anterior-to- outer pad and the metacarpal pads are evidently larger. posterior) the cheek, neck, axillary, and thigh patches (pad no. 1 in Figure 33) and the metatarsal pads are the (Figure 9a & 63). These patches are either whitish, compared to other species of Cricetinae. Feet are hairy yellowish, cream or light buff; the anterior-most smallest. The metatarsal pads are set further back posterior to pads (cf patches are frequently more buffy, and the posterior . Figure 33d). patches tend to be more whitish. The cheek patch which is the most extensive, covers the cheeks, lips, long (Chernova et al. 2022b); those at the base of tail chin and the snout. The roundish neck spot, which is Fur is thick and pretty rough; back hairs are 25–30 mm located just in front of the fore legs, and the axillary spot are longer, reaching ½ of tail length. Colour pattern is behind it, are separated by a dusky upward expansion specialized and the common hamster is one of the most of black hairs from the upper arms (Figure 63). The brownish buff, belly is black and there are contrasting axillary patch tends towards medial expansion which colourful Palaearctic muroid rodents. Upper parts are restricts the black area of the belly (Figure 65). Such a light patches on the contact between the brown and black areas (Figures 61 & 63). Besides this standard constraint is seen in ~ 60% of individuals within the (tricolour) colouration, black individuals (Figure 64) are population and is more common in the west. The thigh patch is the smallest and is prone to obliteration; its locally common, while other variants occur at very low 98 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. presence and size are occasionally asymmetric. Light (white to buff) spots and patches are present behind the ears, on throat (chin streak) and on the chest between forelegs (chest spot); their frequency and size vary among populations (Figure 66). Ears are of same colour as the head and are margined white. Paws are similarly white; white area on the antebrachium, which is of varying length, is usually called the cuff (Figure 63). Young hamsters are of similar pattern, but are darker; in very young individuals, the light patches are less prominent. The penis is approximately 30 mm long when erected; dorsal surface is flat and ventral side is deeply grooved by sulcus urethralis (Reznik et al. 1979). Glans penis is cylindrical with a truncate tip; the width of glans equals approximately ⅓ of its length. The urethral crater is surrounded by 1 central and 2 lateral papillae which are of equal size (Figure 16). Papilla ventralis is flattened and bicuspid; dorsal papilla is absent (Bittera 1918). Baculum is robust with well ossified distal digits and heavily expanded base (Figure 17h). Proximal stalk measures 3.6 mm; the central and lateral digits of distal trident are of approximately same length (2.5 mm; Figure 64: Didier 1953). Females have 2 pairs of each, the pectoral Black (melanistic) morphotype of the common hamster Cricetus cricetus from Thuringia, Germany. Note white snout and and the inguinal nipples (8 nipples in total; Popov paws. Photo courtesy of Wolfgang Hock 1960). The skull is robust, heavy-built and well ridged in adults (Figure 67). The dorsal profile is slightly bent, which is most evident anterior to the naso-frontale suture. Zygomatic arches are moderately to widely expanded and zygomatic width accounts for 56–58% of condylobasal length of skull. Old individuals with fully spread arches reach maximum width just in front of glenoid region. Masseteric plate is well developed; the infraorbital foramen is wide above, narrow and slit-like below (Figure 20a). Rostrum is robust and decidedly wider than the interorbital region. The latter is well constricted with distinct median furrow and raised edges. Temporal ridges merge posterior to the frontals, Figure 65: Ventral side of common hamsters Cricetus cricetus to show but do not fuse into sagittal crest. Frontals are postero- variability in the extent of the axillary light spot (III) and the consequent restriction of the black belly colouration. Light colour medially much constricted and wedge deeply between on the right side of abdomen in specimen (d) is caused by hair loss. the parietals. Braincase is diamond shaped, with Origin of vouchers: a – Tomsk Region, western Siberia, Russian characteristically small and triangular interparietal; a Federation; b, c – Bashkortostan, Russian Federation; d – powerful lambdoidal crest forms a prominent medial Hortobagy National Park, Hungary. Photo: B. Kryštufek. concavity. The occiput is oblique and is clearly seen in SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 99. Figure 66: Variation in colour pattern of the ventral side of Cricetus cricetus: a.c. – antebrachial cuff, c.s. – chin streak, p.s. – pectoral spot, III – axillary light spot. Vouchers originate from: (a) – Kozhevnikovo, Tomsk Oblast, Siberia, Russian Federation; (b) – Kostanay Province, Kazakhstan; (c) – Dunaszeg, Hungary; (d) – Rhine-Westphalia, Germany; (e) – Belgium (modified from Husson 1959). Figure 67: Adult female (top) and male (bottom) common hamster Cricetus cricetus skulls from Dunaszentpal, northwestern Hungary. Note dimorphism in size and shape. 100 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. dorsal view, along with condyles. Bullae are circular and presumably in response to the changing climatic rather large; paroccipital process is well developed and conditions and in accordance with the Bergmann’s rule shifted posterior. Incisive foramina are quite long but (e.g. Smirnov & Popov 1979). Size classes have been still terminate well in front of the molars. Pterygoid classified as distinct taxa, either subspecies or species. processes are high and the interpterygoid vacuity is They are currently synonymized with C. cricetus, largely spacious; hard palate terminates at the posterior margin due to their uniform dental morphology, which is of the molars. Mandible is slender, with high recurved identical to that in the current species (Sutcliffe & coronoid process; angular process is slim and bent Kowalski 1976, Kowalski 2001). Dimensions (length of outwards; articular process is robust. The root of the maxillary tooth-row; in mm) of the large fossil C. cricetus lower incisor forms an evident bulge on the outer wall praeglacialis Schaub, 1930 (= 7.3–9.0) and the small C. of ramus slightly above the level of molars. The root of cricetus nanus Schaub, 1930 (= 6.0–7.4; Pradel 1985) are the upper incisor nearly reaches the posterior level of largely within the variation range for central-European the infraorbital foramen, where forms a swelling. hamsters (= 6.6–8.9; see also account on Number of roots in molars is 4 (M1–2), 3 (M3), and 2 Characteristics). Besides, size varies between years even (M1–3). Molar pattern shows no peculiarities (Figure 68). in the same population; hamsters are on average the largest in the year following the population peak and the Karyotype (2n = 22) consists of 7–9 pairs of biarmed smallest 2 years after the peak. Furthermore, chromosomes (metacentrics and submetacentrics) of interpopulation size differences can be prominent even various sizes; the remaining autosomes are in populations separated by small geographical distance subtelocentric and acrocentric. Sex chromosomes are (Grulich 1987a). On the other hand, no obvious trend biarmed; the X is large and the Y is a rather small in size variation has been evident in recent hamsters element. Fundamental number of chromosomal arms is both at large (Berdyugin & Bolshakov 1998) and locally NF = 42 (Ivanov 1969b, Zima & Král 1984). The (Stefen 2013). karyotype is characterized by high amount of centromeric heterochromatin (Gamperl et al. 1978). Frequency of light colour marks vary among Heterochromatic arms are restricted to sex populations. Hamsters occurring to the west of the chromosomes (Vistorin et al. 1976). river Rhine have higher incidence of white crown and chest spots; the chest spot, chin streak and white Variation and subspecies. Individual variation is antebrachial cuff are also larger (Figure 66). The crown excessive and blurs interpopulational variation. Size spot which is present in 12.5% of hamsters from The varied historically throughout the Pleistocene Low Countries is still present in the Pannonian Basin (Kowalski 2001, Horáček & Lebedová 2022), (Husson 1959), but is largely absent elsewhere. The chin Figure 68: Grinding pattern of upper (a, b, c), and lower (a’, b’, c’) molars in the Common hamster Cricetus cricetus from Vojvodina, northern Serbia. Scale bar = 1 mm. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 101. streak is of variable shape, from short, broad and blunt proportion within the population is usually low to long, narrow and pointed. It is the longest to the west (frequency ≤ 0.01%; Kayser & Stubbe 2000), the main of the Rhine (Schröder et al. 2013) and short or absent source of material was the fur market supplied by to the east of the Urals (Kryštufek et al. 2016). hundreds of thousands hamster pelts. E. g. Gershenson Frequency of presence of the white chest spot is 67– (1946) estimated proportions from a sample of over 2 100 % to the west of the Rhine, 0–8 % in central and million hamster skins collected in Ukraine and Russia Eastern Europe (Schröder et al. 2013) and 1.1% in Asia during 1931–1940. The disadvantage of such huge (Kryštufek et al. 2016). The spot is of smaller diameter samples was a lack of clear description of colour and frequently diffused in the east. The white cuff is variants (Kayser & Stubbe 2000), which may distort the long and present at all times to the west of the Rhine, perception of reality. E. g., Gershenson (1945) treated but is shorter and occasionally absent further east. The hamsters as being dimorphic (black v. tricolour), white thigh spot is omnipresent to the west of the however, his black category possibly included a range Rhine, but was recorded in ~ 87% of hamsters from of dark-coloured individuals (Kryštufek et al. 2016). eastern Europe and Asia (Schröder et al. 2013, Black colour is inherited as a simple autosomal Kryštufek et al. 2016). dominant (Gershenson & Polevoy 1941), whereas albinotic and flavistic variants are recessive (Petzsch The most prominent feature of the individual and 1941, Petzsch & Petzsch 1956). population variability in the common hamster is colour polymorphism, which was described as early as the 17th Black variant is regionally frequent and has been century (e.g. Topsel 1658, Falk 1786, Bechstein 1801, extensively studied. Black and tricolour hamsters mate Gilibert 1805, Pallas 1811, Buhle 1821). List of variants freely (Gershenson & Polevoy 1941, Petzsch & Petzsch includes black (atypical melanistic and melanistic 1956) and have often been found in same litters proper), dark tricolour, bicolour, piebald, white, albino, (Lepekhin 1771, Pallas 1779, Novikov 1935). Black yellow (flavistic), red, sand, ivory, and ‘iron grey’ hamsters are typical of Thuringia (Germany) (Figure coloured hamsters (Petzsch 1936a, 1941, Kayser & 64), parts of Ukraine and eastern European Russia. In Stubbe 2000, Kryštufek et al. 2016). Since their Thuringia, they occupy a fertile area of 70 × 30 km. Figure 69: Colour variation in common hamster Cricetus cricetus showing blurring of tricolour pattern (a) and darkening of pelage (b–f). a – A dull tricolour type which lost light thigh patch (“stavropolicus” variant; Vladikavkaz, Russian Federation); b – a bicolour type which lost all light patches (Kislovka, Tomsk District, western Siberia, Russian Federation); c – a black (atypical melanistic) variant from Novaya Chertoryja, Zhitomir oblast, Ukraine; d – a black variant with light patches from Belgrade, Serbia; e – a black variant with rusty shines on head and rump (Dresden, Germany); f – a black (melanistic) individual from Pișcolt, northern Romania. Photo B. Kryštufek. 102 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Within this area, different populations contain diverse positively correlated with humidity and population proportion of black individuals. During the 1960s, the density (Gershenson 1945). During the 1930s, black proportion of black individuals was 0.5–18.0% per hamsters expanded their ranges in Ukraine, both county (Zimmermann & Handtke 1968, Zimmermann northward (in Chernigov) and southward (in Odessa 1969). In Ukraine in 1930s, black hamsters were tied region) and replaced the tricolour type (Gershenson exclusively to the forest steppe zone which received 1946, Vorontsov 1982). Similarly, in Russia to the north >500 mm of precipitation annually. Their proportion of the Kama River, the black variant strongly across 15 regions varied between 0.00–15.33% (annual predominated in the mid-19th century (Bogdanov 1871), total = 2.05–4.68%). Share of black hamsters was but the tricolour type was widespread a century latter particularly high in 4 regions: Zhitomir (3.11%), (Popov 1960). A similar turnover has been reported Chernigov (3.40%), Kamenets-Podolsk (4.85%) and from the city of Gotha (Thuringia) in the late 18th and Poltava (8.20%) (Gershenson 1945, 1946). In European early 19th centuries (Weissenborn 1839, Zimmermann Russia, black hamsters are abundant in humid forest- 1969). On the other hand, black hamsters are steppe habitats of northern Bashkortostan and adjacent persistently present in Thuringia and the Volga-Kama Tatarstan and Perm. During the 1930s, their frequency region since the mid-18th century (Lepekhin 1771, varied across 49 districts of Bashkortostan between Sulzer 1774, Georgy 1775, Erxleben 1777, Pallas 1779, 0.00–87.12% and was >50% in 15 districts Falk 1786); first reports for Ukraine date back to the (Gershenson 1945). The proportion of black variant mid-19th century at the latest (Kessler 1851). Single Figure 70: Fur colouration in pale common hamsters Cricetus cricetus from Saxony-Anhalt, Germany (a–d) and Ukraine (e, f). Round skins (a–d) are shown in dorsal (top row) and ventral view (bottom row). Voucher (f) is flavistic with white belly and rusty fur between the snot and occipital region. Voucher (e) is light-grey above and blackish-grey below with abundant blackish hairs above; fur around the eyes and ears is light rusty. Note that vouchers (e) and (f) retained light patches on the cheek (I), neck (II), and in the axillary region (III) ( cf. Figure 63). Photo B. Kryštufek (a–d) and Nedko Nedyalkov (e, f) SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 103. black hamsters were found here and there in other parts frequently have their fur interspersed with black hairs, of the species’ range to the west of the Urals. Adaptive which are denser along the spine (Figure 70a). significance of the black coat colour is not clear. Under Depending on their density, the fur assumes different experimental conditions, black hamsters prefer colder shades of grey colour (Figures 70a, b, e & 71a). and moister conditions, while tricolour hamsters select warmer and drier microclimate (Samosh 1969). White variants are linked to the standard tricolour type through a gradation of flavistic modifications with Black hamsters are usually classified as melanistic, various intensity of yellowish or buff shades and with though they invariably show white feet, muzzle, chin whitish or black belly (Figures 70c–f & 71c, d). Just like and ear edge (Figures 64 & 69f); occasionally, they also in black skins, not two light hamsters are identical in have a white pectoral spot. Black hamsters, however, every detail. The pattern of light patches, which is frequently show reddish shine and/or whitish patches typical of tricolour type, is either lost (Figure 70a–d) or (Figure 69c, e). Such hamsters, called ‘atypical retained (Figure 70e, f & 71 c, d), regardless of the melanistics’, are common in Thuringia (frequency = overall colouration of an individual. 60% of black hamsters; Zimmermann 1969) and were reported as single individuals from Rhein-Hesse Common hamster was treated as a polytypic species. (Thomas 1963), Poland, Ukraine, Ciscaucasia (Adygea), Number of subspecies varied widely among authors, and Kazakhstan (Kryštufek et al. 2016). Also described ranging from 3 (Ellerman & Morrison-Scott 1951), 5 as atypical melanistics are blackish hamsters which (Trouessart 1904), 6 (Truessart 1910), 7 (Berdyugin & retain light patches (Figure 68d); they were reported as Bolshakov 1998), 9 (Argyropulo 1933c), 10 (Petzsch single individuals from a comparatively small area 1936b, 1952) or 11 subspecies (Ellerman 1941). between eastern Austria (Bauer 1960), northern Serbia Truessart (1910) still classified black hamsters as (Kryštufek et al. 2016) and Romania (Chişamera et al. subspecies niger Schreber, 1792, with its range in 2023). In captivity, such a hamster from northern Serbia Germany and beyond. Novikov (1935), on the other delivered normal tricolour offspring (Krsmanović et al. hand, dismissed melanism as a taxonomic trait, treating 1988). Dull tricolour hamsters (Figure 69a) were in the it as a colour aberration. Subspecies were largely based past classified as a subspecies in its own right on differences in colour shades, size and skull shape (cf. (stavropolicus). This type is known primarily from steppes Novikov 1935, Surov & Feoktisova 2023). to the north of the Caucasus Mts. (Ciscaucasia), but was Craniometric analyses (Husson 1959, Grulich 1987a, reported also from Thuringia (Zimmermann & Stefen 2013, Kryštufek et al. 2016) provided weak Handike 1968). Light patches are exceptionally entirely support for the subspecific taxonomy; these studies also lost, resulting in a bicolour variant, which is known only showed that colour variants are more diverse (Husson from Ciscauscasia and western Siberia (Kryštufek et al. 1959, Kryštufek et al. 2016) than craniodental size and 2016). To summarize: the black and the tricolour shape. Novikov (1935) categorically claimed that variants are connected through gradations of diverse subspecies lack diagnosability. When experts were atypical melanistics, of which not even two individuals asked to classify museum vouchers into subspecies, are perfectly identical (Zimmermann & Handike 1968). they failed as long as they did not know the collecting site. Husson (1959: 197) similarly concluded that “… ‘White’ hamsters were reported from Thuringia, the one had better abstain from applying terms like Urals (Bechstein 1801), and Bashkortostan (Popov subspecies or geographical race to this situation [in C. 1960). Although such hamsters are rare everywhere, cricetus] which is so strikingly different from the usual they were still the dominant colour variant (n = 50 situations in which these terms are applied.” In a study individuals) in a large sample of skins (n = 73,567) from on geographic variability of colour and size in C. cricetus, eastern Germany, accounting for ~ 80% of all colour we came to similar conclusion: “division of the aberrations (Kayser & Stubbe 2000). Similarly to black common hamster into a subspecies is not congruent hamsters, the white also lack detailed description in the with the pattern in morphological variability (or lack of majority of cases. Nevertheless, at least some were it) and thus obscures reality” (Kryštufek et al. 2016: albinos with red eyes (Bechstein 1801, Schlott 1924, Petzsch & Petzsch 1956). White museum skins 104 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 71: Colour variants in common hamster Cricetus cricetus from Thuringia, Germany. Top row shows uniformly grey hamsters and bottom row shows yellow (flavistic) variants; individual (a) is light grey and (b) is dark grey (atypical melanistic). Note difference in blurring reddish-brown shade in flavistic individuals, which both retain a rusty head. Photo courtesy of Wolfgang Hock 153). Hence, no subspecies are recognized here (cf. also Crimea, European part of Russia, south-eastern Kryštufek 2017e). foothills of the Ural Mts., and Western Kazakhstan), and (5) the Altay lineage (northern and eastern Phylogeographic analyses retrieved significant Kazakhstan, western Siberia and Altay) (Neumann et al. population structuring with 5 allopatric lineages, which 2005, Feoktisova et al. 2017, 2018, 2022, 2023, Korbut diverged during the Last Glacial Maximum. These et al. 2019). Noteworthy, the phylogeographic lineages are (1) Western (Benelux, Germany, western structuring does not match any subspecific division. E. Poland), (2) Pannonian (Czech Republic, Slovakia, g., ssp. canescens with its putative range to the west of the Hungary, Romania), (3) Central (Poland, Belarus, and River Rheine, is not supported by phylogeography, most of Ukraine), (4) Eastern (eastern Ukraine and which was predicted already by Husson (1959). TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Subtribe: Cansumyina – new subtribe Taxonomy. Cansumyina new subtribe clearly differs in Type genus. Cansumys G. Allen, 1928. a set of external and craniodental traits from the remaining Cricetini, which we classify as a subtribe Content. Contains a single monospecific genus Cricetina. Cansumyina contains a single species Cansumys, which is restricted to a small area in central Cansumys canus, hence we provide a detailed description China. in the species account below. In the multi-character cladistic analysis (Ross 1992) and mitochondrial (cytb) Genus: Cansumys G. Allen, 1928 – phylogenetic reconstruction (Jiang et al. 2024), Cansumys Gansu Hamsters emerged as a basal lineage in Cricetini; the divergence time was estimated as 10.37 Mya (CI = 7.81–13.06 Mya) (Pan et al. 2024). Cansumys G. Allen, 1928: 244. Type species is Cansumys canus Allen. Diagnosis and Comparisons. (1) The tail is long (~ A monotypic genus; see species account for further 70% of head and body length) in Cansumyina and details. thickly clad with shaggy hairs which cover the annulation (Figure 73); in Cricetina, the tail is Cansumys canus G. Allen, 1928 – proportionally shorter (<65% of head and body length), sparsely haired and with exposed annulation. (2) The Gansu Hamster rostrum is parallel-sided in Cansumyina (Figure 75) but narrows anteriorly in Cricetina. (3) The interparietal of Cansumys canus G. Allen, 1928: 245. Type locality: Cansumyina is broad and strap shaped (Figure 75), as “Choni [Jonê], southern Kansu [Gansu], China.” opposed to triangular or diamond-shaped in the greater [Cricetulus Tscherskia triton] canus Argyropulo, 1933b: 248. part of Cricetina. (4) The pterygoids are shorter than the Name combination. maxillary tooth-row in Cansumyina (Figure 75), while Cricetulus triton canus Ellerman, 1941: 435. Name they are longer in Cricetina. (5) The coronoid process combination. of the mandible is short and blunt in Cansumyina, and C[ricetulus] t[riton] camus: Chen & Min, 1982: 370. does not extend beyond the level of sigmoid notch Incorrect subsequent spelling of canus Allen. (Figure 75); in Cricetina, the coronoid process is C[ricetulus] cansus: Chen & Min, 1982: 370. Incorrect normally long, slender, and extends beyond the level of subsequent spelling of canus Allen and new name the notch. (6) The upper incisors are thick and combination. opisthodont in Cansumyina (Figure 75) but slender and Cricetuws canus: Chen & Min, 1982: 371. Incorrect orthodont in Cricetina. (7) In Cansumyina, the molars spelling of Cricetulus in combination with canus. are robust (molar row is only slightly shorter than Cricetulus canus: Zhang, Jin, Quan, Li, Ye, Wang & diastema) and surrounded by a bony ridge (Figure 75), Zhang, 1997: 216 (Chinese) & 217 (Eng.). Name but weaker (much shorter than diastema) and with no combination. surrounding ridge in Cricetina. (8) The crowns of the molars are mesodont in Cansumyina (Figure 76b) and Etymology. The name Cansumys is derived from brachyodont in Cricetina (Figure 76a). (9) Mesoloph is ‘Cansu’ (i. e. Kansu, now Gansu) and ‘mys’ (Greek for present on M2 in Cansumyina (Figure 77) but absent in mouse), i. e. a ‘mouse from Gansu’, a province in Cricetina. northwest China, where first specimens were captured. 106 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. The species name canus (Latin male adjective for ‘hoary’ distinct morphological types among the long-tailed or ‘grey’) is an allusion to the colour of dorsal pelage. hamsters collected in Shangluo (Shaanxi) and named them Cricetulus triton and C. canus. Shortly afterwards, Taxonomy. The naming of the Gansu hamster in 1928 Ross (1988) re-examined the type series of Cansumys marked the last discovery of an obviously new type of canus and confirmed its taxonomic distinction from hamster. The animal for long remained known only Tscherskia triton. The latter view was promptly grasped from the type series (type and paratype); it is housed in (Corbet & Hill 1992, Musser & Carleton 1993, 2005, the Museum of Comparative Zoology at the Harvard Pavlinov et al. 1995, Wang 2003, Peng & Zhong 2005, University. Without seeing any of these vouchers, Smith & Hoffmann 2008, Jiang et al. 2015), though Argyropulo (1933b, c) downgraded the taxon to a junior some authors continued to classify the Gansu hamster synonym of Tschersia triton, a view that prevailed for the as a species of Cricetulus (Zhang et al. 1997). Starting next half a century. with 2000, only the minority of authors ranked the Gansu hamster as a subspecies of Tsherskia triton (Luo In a treatise on the mammals of China and Mongolia, et al. 2000, Liao et al. 2007) or even ignored it entirely Allen (1940) refrained from discussing Argyropulo’s (Jiang et al. 2015). Chinese authors provided a detailed classification. He stressed that the relationship between comparison between Cansumys and Tscherskia exposing Cansumys canus and Cricetulus (which in his book included karyological (Yang et al. 2003) and morphological also Urocricetus and Tscherskia) “is apparently not very distinctness (Gu 2005) of the two. Despite all this, the close” (Allen 1940: 781). Despite this, Ellerman (1941) taxonomic and geographic scope of Cansumys canus followed Argyropulo and retained canus as a subspecies remained vague. Several authors (Lu & Wang 1996, of Cricetulus triton. It thus happened that Cansumys canus Zhang et al. 1997, Wang 2003) included into Cansumys stayed in the synonymy of either Cricetulus or Tscherskia also ningshaanensis Song, 1985, as one of its subspecies. (Ellerman & Morrison-Scott 1951, Corbet 1978, Following Musser & Carleton (2005) and Jiang et al. Pavlinov & Rossolimo 1987), or was plainly ignored (2024), we classify ningshaanensis as a member of (Corbet & Hill 1980, 1986, Honacki et al. 1982, Tscherskia (see under that genus). The perception of the Vorontsov 1982). external appearance of C. canus continued to be perplexing and in published works the species is still Since the early 1980s, the Chinese authors turned their portrayed either inaccurately (Peng & Zhong 2005) or attention on the status of Allen’s Gansu hamster. Chen plainly erroneously (Smith & Hoffmann 2008, Pardiñas & Min (1982) demonstrated the existence of two et al. 2017). Figure 72: Distributional range of the Gansu hamster Cansumys canus. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 107. Distribution (Figure 72). The range (estimated area = cricetine (Shenbrot 2017d). In a deciduous broad- 92,870 km2) is situated in Central China between the leaved forest in the Qinling Mts., the Gansu hamster is middle flows of the Huang He and the Yangtze Rivers, one of the most abundant rodents. Its range partly and encompasses southern Gansu, southern Shaanxi, overlaps with that of Tscherskia, however, sympatry of and south-eastern Henan. It stretches between the 103– these hamsters was only rarely reported (e. g. in 106th meridians where tentatively embraced by the Shenzhen; Gu 2005). Allopatry seems to prevail and Ordos Plateau in the north and the Qinling Mts. and was reported in the Qinling Mts. (Li & Wang 1996), the the Dabie Mts. in the south. Because the Gansu Gannan Plateau, and the Dubie Mts. (Huang et al. hamster was in the past not always securely delimited 2008). Altitudinal range of occurrence is 740–3,200 m from Tscherskia triton, part of published distributional (mean ≈ 2,000 m). information remains puzzling. It is widely quoted for Nangxia (Zhang et al. 1997, Wang 2003, Smith & Characteristics. Moderately large hamster with Hoffmann 2008), which is presumably based on a proportionally long tail accounting for 77–82% of head report of Cricetulus triton canus for the hilly South Ningxia and body length (Figure 73). External dimensions: body Loess Plateau range (Zhang & Yu 1995). Peng & Zhong mass = 44–57 g, length of head and body = 129–140 (2005) reported the Gansu hamster for the Ganzi mm, length of tail = 95–109 mm, length of hind foot = Tibetan Autonomous Prefecture in north-west Sichuan. 17.9–20.4 mm, length of ear = 20.6–23.5 mm; means Neither Ningxia nor Ganzi are here accepted as a range for cranial variables (n=20–21) are modified from Gu of C. canus and are therefore not shown in Figure 72. (2005): profile length of skull = 35.42 mm, zygomatic The presence of Cricetulus tscherskia canus on the left width = 18.28 mm, length of maxillary tooth-row = bank of the Huang He River as plotted by Luo et al. 6.17 mm. Ears are large (longer than the hind foot), (2000) is presumably also a misidentified Tscherskia triton rounded and protrude above the fur. They are densely proper. clad with short hairs on both sides. Feet are small with proportionally long fore fingers. Hind foot is hairy The Gansu hamster inhabits deciduous and coniferous around the heel; the nude soles have 6 pads of which mountain forests and is presumably the only arboreal the metatarsal pair is small; the central interdigital pair Figure 73: Museum skin of the type specimen of Gansu hamster Cansumy canus in semidorsal (top), lateral (middle) and ventral (bottom) view (MCZ 23779). Note a white subaricular spot. Photo courtesy of Mark Omura 108 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. of pads is small, while the 2 outer interdigital pads are width = 3.52 mm) than in Tscherskia triton (= 5.39 mm; larger. The thumb of the hind foot is short, its claw Gu 2005). Supraorbital ridges are prominent and extend short and slightly flattened, resembling a nail; claws are backwards from the posterior tip of the frontal process white. The tail is shaggy, thickly covered by 7–10 mm of premaxilla, diverging evenly and following the lateral long fine hairs which hide the underlying annulation; edge of the parietals; ridges are most prominent over hairs are longer at the base and the apical pencil is the orbit, where they form a deep groove in-between. feeble. Dorsal fur is up to 15 mm long, hoary-grey and Incisive foramens are pretty short, the hard palate shaded brown, interspersed with all-black hairs; terminates beyond the posterior level of molars and normally, the hair base is slate grey and the tip is pterygoids are remarkably short. The zygomasseteric whitish. Flanks are lighter and shaded cream; complex is of pseudo-sciuromorphous type. demarcation on the flanks is obscured. The belly is grey; hair bases are slate and tips are broadly whitish or cream. A narrow white streak extends from the chin to the sternum; its hairs are white to bases. There are 2 patches, both white to hair bases, on each side of the head: (1) a subauricular patch immediately below porus acusticus, and (2) a patch on the muzzle across the mystacial pad (Figure 74). The eyes are rimmed by a narrow dusky ring. Ears are dark-brown with a narrow white rim; the inner surface is more blackish. Paws are whitish-grey. The tail is brown-grey all-round, slightly lighter below. Juveniles are duller and have less shaggy tail. Figure 74: Head of the Gansu hamster Cansumys canus. Note white subauricular and mystacial patches. Modified from Gu et al. (2005) The skull is somewhat long and narrow (zygomatic width accounts for ~ 51% of greatest skull length); Zygomatic plate is therefore narrow with emarginated rostrum is proportionally long, narrow and parallel anterior margin and the infraorbital foramen lacks the sided (Figure 75). The nasals are comparatively narrow, outer plate. Zygomatic keel and notch are both absent the parietal bone is longer than wide, and the and infraorbital foramen is not seen from above; the interparietal is broad and strap-shaped. The interorbital anterior edge of zygoma transgresses into the rostrum region is markedly more constricted (mean interorbital as a smooth curve. A pair of grooves extends from the Figure 75: Skull and mandible in Gansu hamster Cansumys canus. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 109. posterior edge of incisive foramens to the posterior Karyotype: 2n = 24, consists of 16 pairs of edge of hard palate. Auditory bullae are large, rounded metacentrics, 4 pairs of submetacentrics and 4 pairs of and closely approximated; their distance at the spheno- acrocentrics; the sex chromosomes have so far not been occipital synchondrosis is less than the width of identified (Yang et al. 2003). interpterygoid fossa. The dorsal profile is evenly convex. Subsquamosal and postglenoid foramens are large. The mandible is slightly more robust that in Tscherskia, with blunter processes; the coronoid process is shorter and does not extend beyond the level of sigmoid notch (incisura mandibulae) (Allen 1928, Ross 1992). The upper incisors are opisthodon and thicker than in other hamsters. Molars are robust and the molar-row is long (only slightly shorter than the diastema). Each row is enclosed by an elevated bony ridge. Molars are mesodont (hypsodont in terminology of Ross 1992) (Figure 76), their height from alveoli to crown amounting to 1.5–2.5 mm. Roots of the lower molars Figure 76: Lingual view of the lower molar row with slightly worn M cusps in (a) Cricetus cricetus and (b) Cansumys canus. Note the 2–3 overlap that of the incisor in lateral view and close in old adult age. The lower molars wear earlier than the difference in height of cusps (1) relative to crown height (2) in upper ones. Well-worn molars display enclosed pits brachiodont (a) versus mesodont (b) molars. M1 – 1st lower molar. Photo Mark Omura (b) and B. Kryštufek (a) between each pair of major cusps (Figure 77). Mesoloph, a buccal projection of the endoloph (the Variation and subspecies. Monotypic. Earlier reports enamel ridge connecting the protocone and hypocone) on C. canus as a polytypic species (with ningshaanensis and is present on M2, which is presumably a plesiomorphic the nominal subspecies) resulted from flawed trait in hamsters (Ross 1992). Internal folds on M1-2 delimitation between Cansumys and Tscherskia; (particularly the internal fold if1 on M1) remain ningshaanensis actually belongs to the latter (see the confluent with primary folds even in worn molars. above account on Taxonomy). Anterior conuls of M1 are large. Figure 77: Grinding pattern of upper (a, b, c) and lower (a’, b’, c’) molars in the Gansu hamster Cansumys canus from southern Gansu, China. m – mesoloph. Lingual is to the left; scale bar = 1 mm. 110 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Tribe: Mesocricetini – New Tribe Taxonomy. Mesocricetus was regarded as the most nucleotide sequences and in morphological and aberrant member of Cricetinae already by Miller (1912). chromosomal data. In Mesocricetini, (1) the Early cladistic analyses (Ross 1992, Potapova 2005), subauricular dark stripe is present (Figure 9), while it is however, placed the genus deeply inside Cricetini and absent in the remaining true hamsters; (2) the sternal only subsequent attempts, based on chromosomal data patch is present (Figure 81) but absent in all other true (Romanenko et al. 2007) and nucleotide sequences hamsters except Allocricetulus eversmanni; (3) the soles are (Neumann et al. 2006, Lebedev et al. 2018a) retrieved largely nude between the metatarsal pads and the heel Mesocricetus as a sister group to tribe Cricetini (Figure 1). (Figure 80) (soles are hairy at least posterior to pads in Mesocricetus lineage therefore deserves to be classified as the remaining true hamsters); (4) papillae foliatae are a new tribe Mesocricetini. arranged in 2 rows but in 1 row in the remaining true hamsters (Vorontsov 1958); (5) gallbladder is present, Based on molecular clock, the divergence between but is absent in the remaining true hamsters (Carleton Mesocricetini and Cricetini was estimated at 7.6 ±0.2– & Musser 1984); (6) intestine is long (> 5.5-fold the 10.8 ±1.9 Mya, depending on the calibration point head and body length); the remaining true hamsters, (Neumann et al. 2006). Lebedev et al. (2018a) arrived at except Cricetus, have this quotient <5.0 (Vorontsov a slightly older estimate of 11.65 Mya (CI = 9.69–13.96 1962, 1982); (7) mesolophid is present (Figures 86 & Mya). Using chromosomal data, Romanenko et al. 95), but is absent in the majority of true hamsters (Ross (2021) concluded that all major lineages of true 1992); (8) M3 is larger than M2 (M3 is smaller than M2 in hamsters, including Mesocricetus, diverged in a quick the remaining true hamsters; Gromov et al. 1963, Ross succession in the earliest Late Miocene which is a 1992); (9) 2nd and 3rd molars, both upper and lower, are remarkable match with the estimates by Neumann et al. long and relatively narrow having width-to-length ratio (2006) and Lebedev et al. (2018a). Contrary to this, < 0.75 (the ratio is 0.80–1.00 in the remaining hamsters; Wang et al. (2024) estimated TMRCA, by using a Lozan 1971); (10) rostrum is rectangular with parallel complete genome and transcriptome, between lateral margins (Figures 85 & 94); in the remaining true Mesocricetus and Cricicetulus griseus (= barabensis) at 29.4 hamsters (except Cansumys), rostrum is the widest at Mya. This estimate heavily predates the appearance of nasolacrimal capsule; (11) subsquamosal foramen is golden hamsters in fossil record. Specifically, absent and, as a consequence, hamular process is not Mesocricetus was present in the Eastern Mediterranean separated from squamosal (Figures 85 & 94); and the Caucasus regions since the Late Miocene subsquamosal foramen is present in the remaining true (Vereshchagin 1959, Vasileiadou & Sylvestrou 2022) hamsters, dividing hamular from squamosal (the and throughout the Pliocene (Turnbull 1975, Peshev et foramen is heavily squeezed and slit-like in Tscherskia); al. 2004). (12) entepicondylar foramen is absent in the distal end of humerus (Figure 78), but is present in the remaining Type genus. Mesocricetus, Nehring, 1898. true hamsters (Nehring 1898c); (13) number of mammae is high (> 10), while all the remaining true Diagnosis and Comparisons. Mesocricetini new tribe hamsters have 4 pairs of mammae (Figure 11) belongs to Cricetinae as evident from its morphology (Argyropulo 1933c, Ellerman 1941); (14) trident of the (e. g. bicuspidate dentition and the presence of inner baculum is largely cartilaginous even in adults (Figure cheek pouches) and phylogenetic analyses based on 17i), but is osseous in the remaining true hamsters nucleotide sequences (Steppan & Schenk 2017). On the (Argyropulo 1933c); (15) diploid number of other hand, Mesocricetini differ from the remaining chromosomes is high (2n = 38–44), but lower (2n = tribes of Cricetinae, i. e. Cricetini and Urocricetini, in 112 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. 20–34) in the remaining true hamsters (Romanenko et Semicricetus nor Mediocricetus have been proposed as al. 2007). taxonomic names. Taxonomy. Mesocricetus was proposed as a subgenus of Cricetus (Nehring 1898c) and retained as such still in the 1970s (Trouessart 1904, Heptner 1926, Aharoni 1932, Argyropulo 1933b, c, Neuhäuser 1936, Vinogradov & Gromov 1956, Anderson & Sinha 1972, Ching-Mei & Anderson 1975, Kuznetsov 1975). On the other hand, only 2 years after the establishment of Mesocricetus, Satunin (1900) elevated its rank to a genus in its own right. Satunin’s arrangement gradually prevailed (Dombrowski 1907, Miller 1912, Călinescu 1931b, Vinogradov 1933, Ellerman 1941, Vinogradov & Figure 78: Ventral view on the distal portion of right humerus Argyropulo 1941, Kuznetzov 1944, Ellerman 1948, – demonstrating the absence (a – Mesocricetus auratus) and presence (b Ellerman & Morrison-Scott 1951, Gromov et al. 1963, Cricetus cricetus ) of entepicondylar foramen (ef). Acronyms: ca – capitellum; cf – coronoid fossa; hs – humeral shaft; le – lateral and subsequent authors) and was not challenged since epicondyle; lr – lateral epicondylar ridge; me- medial epicondyle; tr the 1950s. – trochlea. Content. The new tribe contains the genus Mesocricetus between the large Nehring (1898c) defined Mesocricetus as an intermediate Nehring, 1898, with 4 recent species (see below). were in his time clumped under Cricetus and small hamsters, which Cricetulus. Because of its Genus: colourful pelage and strongly ridged skull, many authors Mesocricetus Nehring, 1898 – saw the nearest relative to Mesocricetus in Cricetus (e. g. Golden Hamsters Argyropulo 1933b, c), despite clear differences between them in zygomasseteric structure and baculum. Mesocricetus Phylogenetic reconstructions based on chromosomal Nehring, 1898c: 494. Type species by subsequent designation (Aharoni 1932: 172) is data (Romanenko et al. 2007) and molecular markers Cricetus nigricans (Neumann et al. 2006, Lebedev et al. 2018a) showed Brandt (= Mesocricetus raddei ). that Mesocricetus is a sister genus to Cricetini (Figure 1). Etymology. Mesocricetus is an amalgamated name consisting of the Greek ‘ With the exception of Ognev & Heptner (1927), who μέδος’ (‘ médos’, i.e. ‘medium’) and classified Allocricetulus eversmanni into Mesocricetus, the Cricetus for hamsters (see the Etymology under Cricetus taxonomic scope of golden hamsters was not ), therefore a hamster of medium size or “Mittelhamster” (Nehring (1898c: 494). questioned ever since Nehring’s (1898d) revision. Number of species was, however, for long contested Nomenclature. and varied between a single polytypic species (auratus; In a footnote on p. 494, Nehring (1898c) discussed the (in)appropriateness of Ellerman & Morrison-Scott 1951, Vereshchagin 1959, Mesocricetus as a combination of different languages, the Latin and Harrison & Bates 1991), 2 species (a polytypic auratus Greek ( and raddei; Vinogradov & Argyropulo 1941), 3 species vox hybrida ). Nehring admitted that the new name combination could be all-Latin and quoted two (a polytypic auratus, newtoni and raddei; Ellerman 1941, possible solutions: ‘Semicricetus’ and ‘Mediocricetus’. Corbet 1978, Corbet & Hill 1980, 1986), 5 species Nevertheless, he concluded that “The Greek language (auratus, brandti, koenigi, newtoni, raddei; Trouessart 1904), is much more suitable for forming compounds” (Die or 6 species (nigriculus in addition to 5 species griechiche Sprache ist zur Bildung von recognized by Trouessart l. c.; Dombrowski 1907). This Zusammensetzungen viel geeigneter) and chose number stabilized at current 4 species (e. g. Honacki et Mesocricetus al. 1982), following revisions by Vorontsov (1960), as this particular combination captures his intentions more accurately than any other. Neither Hamar & Schutowa (1966), and Lyman & O'Brien SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 113. (1977). Subsequent phylogenetic reconstructions either as distinct species (auratus and raddei; Vinogradov confirmed the 4-species taxonomy of Mesocricetus & Argyropulo 1941) or subspecies of auratus (Neumann 2007, Neumann et al. 2006, Lebedev et al. (Vereshchagin 1959), or as independent species groups 2018a). (Hamar & Schutowa 1961). Speculations on the phylogenetic relationships between Molecular phylogenies uniformly retrieved tandem species coincided with the progress in karyological groups of golden hamsters, the auratus–raddei tandem analyses. Since the chromosomal number is much and the brandti–newtoni tandem (Neumann et al. 2006, higher in Mesocricetus than in the remaining hamsters, the Lebedev et al. 2018a, Steppan & Schenk 2017). idea of polyploid evolution was launched in the 1950s. TMRCA for recent species is estimated at 2.5–2.7 Mya The hypothesis proposed a hybridogenic origin of M. (Neumann et al. 2006), hence suggesting speciation auratus (2n = 44) from Cricetulus griseus (= barabensis) and events during the Lower Pleistocene. Specifically, the Cricetus, each with 2n = 22 (Sachs 1952, Tobias 1953). divergence times between pairs of species were It was therefore claimed that M. auratus was a tetraploid, estimated at 1.81 Mya (CI = 1.04–2.61 Mya) for auratus– while both parental species were putatively diploids. brandti (Lebedev et al. 2018a), 1.2–1.5 Mya for auratus– The hypothesis was seemingly concordant with other raddei, and 1.7-1.8 Mya for brandti–newtoni (Neumann et odd peculiarities of M. auratus and its congeners, al. 2006). specifically its high nipple counts (14–22 mammae; 8 mammae in putative parental species), a colourful Taxonomic status of species was tested in interspecific pelage (similarly as in Cricetus) with only partially black hybridization trials which included all species except underside (black throughout in Cricetus but light in raddei. Trials between auratus (2n = 44) and brandti (2n Cricetulus), and small distributional range (ranges are = 42) invariably failed (Matthey 1959, Todd et al. 1972, large in Cricetus and majority of Cricetulus). It was further Lyman & O'Brien 1977). Early attempts to cross newtoni suggested that a putatively tetraploid Mesocricetus have (2n = 38) and auratus (2n = 44) similarly failed (Marches arisen from diploids in the recent period (Sachs 1952). 1964a, b), but subsequent efforts resulted in sterile This hypothesis was refuted shortly afterwards (White offspring with intermediate chromosomal count (2n = 1959) and subsequent chromosomal banding analyses 41; Raicu & Bratosin 1966, 1968, Todd et al. 1972). provided strong argument against polyploidy in golden Tests between newtoni and branti produced hybrids with hamsters (cf. Gamperl et al. 1978). 2n = 40, but their sterility / fertility has not been assessed (Raicu et al. 1972, Todd et al. 1972). Another hypothesis on the evolution of golden hamsters presumed gradual reduction of diploid As is the case with Cricetinae in general (Ross 1992), chromosomal number through successive centric the fossil record contributed little towards clarification fusions: 2n = 44 (auratus) → 42 (brandti) → 38 (newtoni) of the evolution of golden hamsters. Specifically, names (Hamar & Schutowa 1966). Based on differential of recent species were attributed to fossil material quite staining of chromosomes (G-banding), Popescu & arbitrarily (Vereshchagin 1959). Mesocricetus rathgeberi DiPaolo (1980) agreed that auratus was the common Pieper, 1984, from the Southern Aegean Island of ancestral species but suggested independent evolution Armathia (near Kasos) and presumably of Holocene for brandti and newtoni. Hamar & Schutowa (1966) age is worth mentioning. This was a large golden further divided the genus into 2 major groups, hamster, of similar size as M. raddei, with strongly ridged separated by the Caucasus: the monospecific raddei skull and deep interorbital groove between the ridges group to the north of the Caucasus and the lineage with (Pieper 1984). Pavlinov (2003) included rathgeberi on the the remaining golden hamsters (auratus, brandti, newtoni) list of recent mammals, albeit with a question mark. occurring to the south of the Caucasus Mountain chain. This idea was not a novel since several earlier authors Distribution. The extant species of golden hamsters distinguished between the larger black-bellied hamsters have allopatric distributions in the north-eastern corner of Ciscaucasia from smaller hamsters with light bellies of the Mediterranean Sea and around the Black Sea, occupying Transcaucasia. These groups were classified 114 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 79: Distribution of the extant golden hamsters Mesocricetus. Note that species ranges are allopatric. reaching the Caspian Sea in the east (Figure 79). Their differences between the two genera (Figure 9). total range is small (area ≈ 660,000 km2) and 2 species Characteristic of Mesocricetus is a dark subauricular (auratus and newtoni) have the most restricted (shoulder) stripe, which is followed by light neck distributions of any hamsters (area < 40,000 km2). The (collar) patch (both are absent in Cricetus), and a Pleistocene ranges of at least 3 species (auratus, raddei, transverse sternal stripe, which is nearly always darker newtoni) exceeded the current ones (see species accounts than the rest of the underside (see also under M. raddei) for further details). (Figures 84, 90, 93 & 98). Characteristics. Form is robust and chunky; the eyes are fairly large (Figures 83, 88, 92 & 97). The ears are of moderate size, pigmented and clad with short fine hairs on both sides (Figure 8). Tail is short and stubby (Figure 97), concealed in fur; its surface shows no traces of scales or annulations, but is densely hairy, hairier below than above. Feet are comparatively short and broad with 4 and 5 fingers on front and hid feet, respectively; the front thumb is reduced. Soles and palms are nude, with 5 and 6 tubercles, respectively. All plantar pads are of similar size, however, the metacarpal pads are significantly larger than any of the 3 interdigital pads Figure 80: Left palm (left) and sole (right) in Syrian golden hamster (Figure 80). Fur is moderately long (10–14 mm on the Mesocricetus auratus. Digits are shown in Roman numerals (thumb = mid-back), dense and very soft; density of hair fibres is I) and interdigital pads are shown in Arabic numerals; pads: mm / largest on the back, it declines gradually towards the MM – medial metacarpal / metatarsal pad, ml / ML – lateral metacarpal / metatarsal pad. flanks and is the least dense ventrally. Hairs at the tail base are noticeably longer from those on the rump; the Females invariably have > 10 nipples (Figure 11b), but terminal pencil is rather short (length = 1.5–4.5 mm). their number varies within species on the one hand and Mystacial vibrissae measure up to ~ 35 mm. is poorly documented in the literature on the other Colouration is highly distinctive and although at glance hand. Ross (1992) gave range as 14–22; the maximum similar to that of Cricetus, there are important SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 115. Figure 81: Skins in dorsal (top row), ventral (middle row) and lateral view (bottom row) of golden hamsters: a – Mesocricetus auratus (Syria); b – M. raddei (Dagestan, Russian Federation); c – M. brandti (Sirbasan, Kars, Turkey); d – M. newtoni (Shabla, Bulgaria). Photo: C. Mlinar (c) and B. Kryštufek (a, b, d). Inset (c) is replicated from Kryštufek & Vohralik (2009: 55, Figure 26); reproduced with permission of the Science and Research Centre Koper. 116 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. is possibly from Kuznetzov (1944), who reported for however, is frequently flattened from the inner or the Mesocricetus 7–11 pairs of nipples, but gave no further outer side, or both (Figure 20b, h). details. In M. auratus, which was studied in detail, the nipple count varies between 11 and 17 (median = 14); Cranial profile is slightly convex; brain-case is diamond 44% of captive-born females (n = 168) deviated from shaped, short and deep. The occipital region is inclined the median value (Anderson & Sinha 1972, Ching-Mei towards condyles, which are shifted backward and & Anderson 1975). Nipples are continuous along the clearly seen in dorsal view. Nasals are long with a mammary line with 2 pairs of each, the pectoral, pointed tip; posteriorly, they reach well behind the abdominal and inguinal mammae. Supernumerary lacrimal bone. Parietals are squeezed by the expanded nipples are located on the anterior or the posterior end squamosals. Zygomatic arches are heavy and parallel; of the mammary line. interorbital region is constricted and is much narrower than rostrum. Supraorbital ridges are present in adults Glans penis is the simplest of any true hamsters and the lambdoid crest is strong. Palate extends behind (Vorontsov 1982). The surface is densely covered by the tooth row; pterygoid fossa is deep. Auditory bullae numerous spines, which are absent around the meatus are relatively large and oval-shaped. Mandible shows no urinarius. Three papillae stick from meatus, the central peculiarities, except for long and powerful coronoid and 2 lateral papillae; the lateral papillae are expanded process. distally (Figure 16). The proximal stalk is short and strongly built with an expanded base; it is grooved Incisors are robust but show no peculiarities. The two ventrally. The three distal processes are long and widely posterior molars are not much reduced in comparison expanded in their middle portion, but the lateral two to the 1st molar; besides, they are narrower than in other converge distally with the central element into a pointed true hamsters. The anterior–to-posterior trend of size apex. Lateral processes are longer than the central one reduction, which is obvious in the maxillary row, is (Figure 17i). The baculum of M. auratus shows three or entirely absent in mandibular molars. The M3 tends to four ossification centres: 1 primary for the stalk, 1 be the largest and M1 the smallest molar. The numbers secondary centre for each of the 2 lateral prongs, and of alveoli are 4, 4, 3 for M1, M2, and M3, respectively, sometimes the 4th centre for the medial distal process. and 2 for each lower molar. Ossification of distal trident starts on lateral digits at the age of ~ 6 months; central digit remains cartilaginous, Key to species though some ossification may take place at the age of ~ 1 year (Callery 1951). In old males, processes ossify with Species of golden hamsters differ in fur coloration (cf. the proximal stalk into a single bony element. Figure 81) however, individual variation is significant and not all vouchers can be securely classified on this Skull is easily recognizable by a combination of ground. For achieving reliable classification, we advise prominent ridges, a long, heavy rectangular rostrum the readers to consult illustrations and text below. with parallel lateral margins, small and frequently triangular interparietal, short incisive foramina, which 1a) Dorsal pelage is bright golden-brown, the posteriorly do not reach molar line, and the subauricular stripe is never black, the sternal patch pseudosciuromorphous zygomasseteric structure is usually buff and never pure black, belly is (Figures 85 & 94). The inferior maxillary root of whitish-creamy (Figure 81a); present in Syria and zygoma lacks the forwardly extended plate that Turkish provinces of Hatay, Kilis, Gaziantep, and normally forms the external plate of the infraorbital Şanlıurfa ……………………...…………. auratus foramen (Figure 19b2). Hence, when viewed from 1b) Dorsal pelage is grey or brown-grey, the above, the anterior margin of the superior zygomatic subauricular stripe is black, the sternal patch is root forms an unbroken curve to maxilla-premaxillary pure black, belly is grey or black (Figures 81b–d); suture. The zygomatic notch and spine are also absent present in south-eastern Europe, southern (Figure 19a2). In the absence of the outer plate, the European Russia, Georgia, Armenia, Azerbaijan, infraorbital foramen assumes an oval outline which, Iran, and Turkey in Asia (absent in the provinces SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 117. of Hatay, Kilis, Gaziantep, and Şanlıurfa) short (Figure 85). The auratus group contains 2 species ………………………………………………... 2 (auratus and raddei) which presumably diverged 1.2–1.5 2a) Size is larger (head and body > 150 mm); Mya (Neumann et al. 2006). In fossil record, they can underside usually dark-grey or black (Figures 81b be traced back to the Late Pleistocene (auratus; & 90); occipital region is heavily inclined towards Tchernov 1975) and Middle Pleistocene (raddei; condyles; temporal ridges in full-grown individuals Argyropulo 1941b, Vereshchagin 1959, Baryshnikov & reach lambdoidal crest (Figure 85); mesopterygoid Baranova 1983). fossa (mean width = 3.28 mm) is on average conspicuously wider than incisive foramina (width These two golden hamsters are externally the most = 2.34 mm); 4 autosomal pairs are acrocentric dissimilar in the genus Mesocricetus and their ………………………………………..…. raddei phylogenetic closeness was never assumed in the times 2b) Size is smaller (head and body < 165 mm); of traditional morphology-based taxonomy. Hamar & underside usually light-grey (Figure 81c, d); Schutowa (1966) even proposed for raddei a basal occipital region is not particularly inclined towards position in the genus. condyles, or is nearly orthogonal (Figure 94); mesopterygoid fossa (mean width = 2.3 mm) is on Mesocricetus auratus (Waterhouse, average inconspicuously wider than incisive 1839) – Syrian Golden Hamster foramina (width = 2.2 mm); at most 2 autosomes are acrocentric ………….…………………….3 3a) Sternal patch is shorter (length < 35 mm), Cricetus auratus Waterhouse, 1839a: 57. Type locality: frequently surrounded by white patches and “Aleppo”, Syria. Cricetus (Mesocricetus) auratus: Nehring, 1898d: 389. Name occasionally split medially (Figure 98); usually a combination. single oblique black stripe (subauricular stripe) in M[esocricetus] auratus: Satunin, 1900: 301. First use of the front of light collar stripe (Figures 81c & 97); current name combination. occipital stripe usually missing (Figure 81c); 2n = M[esocricetus] aureatus: Meulen & Kolfschoten, 1986: 206. 42; present in south-western Asia and Dagestan Incorrect subsequent spelling of auratus . ………………………………………….. brandti 3b) Sternal patch is longer (length > 50 mm), not surrounded by white patches and never split Etymology. Species epithet auratus is a Latin adjective (Figure 93); usually 2 oblique black stripes meaning ‘ornamented with gold’, in allusion to the fur colouration in the species. The adjective derives from (subauricular stripe and postero-lateral extension the noun ‘aurum’ meaning ‘gold’. of sternal patch) anteriorly and posteriorly to light collar stripe (Figures 81d & 92); occipital stripe bold and long (Figure 81d); 2n = 38; present in Taxonomy. Because auratus is the oldest name in south-eastern Europe ……….….……..…ne Mesocricetus, it was occasionally used to incorporate all wtoni species group names of golden hamsters (e.g. Ellerman Species group & Morrison-Scott 1951, Harrison & Bates 1991). This, auratus however, was an extreme view and more frequently auratus was defined with the inclusion of brandti The auratus group is characterized by nucleotide (Argyropulo 1933b, c, Ellerman 1941, 1948, sequences (Neuman et al. 2006, Lebedev et al. 2018a) Vinogradov & Gromov 1956) and also newtoni and higher diploid number of chromosomes (2n = 42– (Vinogradov & Argyropulo 1941). Current taxonomic 44). Gland penis is cylindrical and parallel sided. scope of auratus was set by Hamar & Schutowa (1966). Temporal ridges are well developed and reach the Syrian golden hamster is well defined by nucleotide lambdoidal crest in old individuals; they bent medially sequences, diploid number of chromosomes, and anterior to the fronto-parietal suture. In very old external morphology. It is a sister species to M. raddei individuals, the ridges lie close together with medial (Lebedev et al. 2018a). groove in-between. The frontals are not much compressed posteriorly and the fronto-parietal suture is 118 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 82: Distribution of the Syrian golden hamster Mesocricetus auratus. Distribution. Syrian golden hamster occupies the Characteristics (Figure 83). External appearance is smallest area (= 24,125 km2) of any true hamster. Range same as for the genus, the size, however, is on average is spread in the bordering area between south-eastern slightly smaller than in brandti and newtoni. Lyman & Turkey and north-western Syria (Figure 82). The great O’Brien (1977) reported body mass in 2-year-old majority of records come from the Halab Province captive bread animals as 97–113 g (mean = 105 g) for (Syria); the species is known also from Idlib and Turkish auratus and 137–258 g (mean = 163 g) for brandti. provinces of Gaziantep and Kilis. There are 2 outliers, Dimensions in free-living M. auratus are: body mass = the eastern in Şanlıurfa (Yiğit et al. 2003) and the 82–175 g, length of head and body = 128–165 mm, southern in Hama (Aidek & Amr 2021). In Syria, the length of tail = 13–21 mm, length of hind foot = 19.0– species presumably reaches the southern Homs plains 22.0 mm, length of ear = 18.0–22.5 mm; condylobasal where it is prevented from further spreading by the length of skull = 30.1–38.6 mm, zygomatic width = north-western extension of the Syrian Desert and the 17.2–19.8 mm, length of maxillary tooth-row = 5.0–6.6 Palmira Mountain range (Aidek & Amr 2021). A mm. Dorsal fur is deep golden brown with rufescent historical record from 1949 from Hatay (Eisentraut hue over the body and particularly along the spine and 1952) remains unconfirmed, and reports for Lebanon on rump; the auricular region and the head are faintly and Israel (Musser & Carleton 1993) are most likely yellow tinted. The sides of the muzzle, throat, and erroneous (Shehab et al. 2004). Syrian golden hamster under parts of the body are white and frequently tinted was, however, present in Israel during the Last Glacial creamy; hair bases are slate (Figures 81a & 83). The Maximum but its range shrunk northwards since then subauricular stripe is a mixture of brown and black (Kryštufek & Vohralík 2009). Mesocricetus auratus hairs, and varies from deep brown to blackish brown; occupies steppes on sandy clay sediments overlying posterior to it is white collar stripe which connects to limestone (Gattermann et al. 2001, Kryštufek 2017a); the underside. Dark-tipped hairs cluster on the crown, such habitat is now largely transformed into rain-fed forming a blackish-brown patch of moderate size crop fields and rocky pastures. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 119. Figure 83: Syrian golden hamster (Mesocricetus auratus). Photo courtesy of Christian Kern. Used with permission of the Science and Research Centre Koper. Figure 84: Ventral side of Syrian golden hamsters Mesocricetus auratus demonstrating variability of the sternal patch. 120 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. which, however, is frequently blurry. Sternal patch is of The usual number of nipples is 14, but this varies widely variable size, form and colour (Figure 84). It is (range = 11–16). The glans penis is rather narrow but exceptionally an isolated patch but more commonly a deep; length = 3.6 mm, width = 2.55 mm, depth = 2.9 21–32 mm long band which is frequently split by white mm. Lateral papillae are decidedly larger and longer medial stripe. The patch is usually golden brown and than the central papilla; their distal ends are expanded frequently with admixture of black-brown hairs, which (Figure 16). The entire baculum is ~ 4.3 mm long, and may aggregate into a blackish area of variable size. Tail 1.3–1.4 mm wide at its triangular base (Kryštufek & is of same colour as the back except for whitish terminal Vohralík 2009). hairs. Feet are covered by white to light cream short hairs. The ears are pigmented grey and covered by The skull does not deviate appreciably from the creamy white fine hairs. Various colour variants were appearance typical of the genus (Figure 85). Width produced in captivity (Robinson 1968). across zygomatic arches accounts for 53.2–57.8% of Figure 85: Skull in golden hamsters from the auratus species group (top to bottom): Mesocricetus auratus and M. raddei nigriculus (Rostov Oblast, Russian Federation). SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 121. Figure 86: Grinding pattern of upper (a, b, c) and lower (a’, b’, c’) molars in the auratus species group of golden hamsters: a, b – Mesocricetus auratus, c – M. raddei raddei. m – mesolophid. Scale bar = 1 mm. condylobasal length. The masseteric plate is short (~ 2.4 Code); see also Pavlinov & Rossolimo (1987: 172– mm) and the infraorbital foramen is oval (Figure 20h). 173) who referred to Article 59b of the 2nd edition of the Code (ICZN 1964). Replaced with Cricetus Pterygoids normally converge anteriorly at the hard nigriculus Nehring, 1898. palate, hence the interpterygoid fossa is triangular in the Cricetus nigricans var. Raddëi Nehring, 1894b: 149. Type greater part (= 71%) of the skulls; it is rectangular in 9% locality: “Ober Samur [upper valley of the Samur of individual and intermediate in the rest (Kryštufek & River]”, with a footnote: “Der Samur ist ein Fluß in Vohralik 2009). Dentition shows no peculiarities Dagestan [Samur is a river in Dagestan]”, Russian (Figure 86a, b). Federation. The type is deposited in Berlin (NHMBe 45420) and not in ZIN St. Petersburg Karyotype: 2n = 44, NF = 82, NFa = 78; 18 autosomal (Ross 1992: 322) (see also Pavlinov & Rossolimo pairs are bi-armed, and further 3 pairs are acrocentric. 1987: 172, Baranova & Gromov 2003: 49). Both sex chromosomes are large metacentrics; the X is Cricetus Raddei: Nehring, 1898a: 182. New rank for raddei the largest element in the set (reviewed in Arslan & Nehring. Zima 2014). Note that old reports of 2n = 38 are Cricetus nigriculus Nehring, 1898c: 495. New replacement erroneous (Robinson 1968). name (nomen novum) for nigricans Brandt. In accordance with Articles 67.8 and 72.7 of the Code Variation and subspecies. Monotypic (Kryštufek (ICZN 1999), the replacement name has the same 2017a). name-bearing type (and type locality) as Brandt’s name, i.e. “montagnes du Caucase [mountains of the Mesocricetus raddei (Nehring, 1894) – Caucasus]” (Ménétries 1832). Ellerman & Morrison- Radde’s Golden Hamster Scott (1951: 630) restricted the type locality to “River Malka, mountain of middle part of Northern Cricetus nigricans Brandt, 1832: 22 (in Ménétries 1832). Cricetus (Mesocricetus) nigriculus: Caucasus”, Dagestan, Russian Federation. Nehring, 1898d: 380. Permanently invalid as secondary homonym of Hamster nigricans Lacépède, 1799 (= Cricetus cricetus) Cricetus (Mesocricetus) Name combination. (Nehring, 1898c: 495) and replaced before 1961 but combination. Raddëi: Nehring, 1898d: 381. Name no longer considered congeneric (Article 59.3 of the 122 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. M[esocricetus] Raddei: Satunin, 1900: 301. First use of the Distribution range of Radde’s golden hamster (surface current name combination. area = 103,520 km2) encompasses the northern and Mesocricetus nigriculus: Satunin, 1901: 40. New rank and eastern slopes of the main Caucasian ridge, and the name combination. steppes of Ciscaucasia between the Sea of Azov and Mesocricetus raddei avaricus Ognev & Heptner, 1927: 142. Black Sea in the west and the Caspian Sea in the east Type locality: “Near the (village) aoul Khunsakh, (Figure 87). The species is nearly endemic to Russian Avarsky district. Province of Daghestan, 5530 feet Federation with a single record being reported from the [1,685 m] alt.”, Russian Federation. Mtskheta-Mtianeti region in north-eastern Georgia Cr[icetus] (Mesocricetus) raddei nigriculus: Argyropulo, (Bukhnikashvili 2004). Inside Russia, Radde’s hamsters 1933b: 244. Name combination. occupy (north-west to south-east) Rostov Oblast, Cr[icetus] (Mesocricetus) raddei avaricus: Argyropulo, 1933b: Krasnodarskiy Kray, Adygeya, extreme western 244. Name combination. Kalmykiya, Karachayevo-Cherkesiya, Stavropol’skiy M[esocricetus] r[addei] nigriculus: Kuznetzov, 1944: 323. Kray, Kabardino-Balkariya, Severnaya Osetiya, First use of the current name combination. Ingushetiya, Chechniya, and Dagestan. Presence in M[esocricetus] r[addei] avaricus: Kuznetzov, 1944: 323. Kalmikiya (Yashalta and Gorodovikovskiy) is said to be Name combination only temporary (Sandzhiev et al. 2013). Mesocricetus auratus raddei: Ellerman & Morrison-Scott, 1951: 630. Name combination. Prior to 1940, the north-western border tentatively Mesocricetus auratus nigriculus: Ellerman & Morrison- followed the line River Malka–Manych–Sal’sk Scott, 1951: 630. Name combination. (Argyropulo 1941a), but Radde’s golden hamsters Mesocricetus auratus avaricus: Ellerman & Morrison-Scott, subsequently spread westward for > 200 km and 1951: 630. Name combination. reached the line Delta of Don River–Bay of Taganrog; cf. Figure 1 in Yakovlev & Kolesnikov (1954) and Figure Etymology. Species epithet raddei is eponym for 11 in Bobrov et al. (2008). The expansion started in Gustav Ferdinand Richard Radde (1831–1903), a 1947, when the population density was very high German naturalist who provided the type specimen (Luk'yanchenko 1954, Yakovlev & Kolesnikov 1954). now deposited in Berlin (NHMBe 45420). Radde is Hamsters subsequently disappeared from the Don remembered for his explorations in the Caucasus and Delta (Minoransky et al. 1997), and currently the most adjacent regions of the Russian Empire and has further exposed occurrence is in Maykop. During the Middle eponyms in mammalogy, ornithology, herpetology, etc. and Upper Pleistocene, Radde’s hamsters occurred southward of their current presence in north-eastern Taxonomy. Shortly after Brant's (1832) recognition of Azerbaijan and northern Georgia (Vereshchagin 1959, Radde's golden hamster as Cricetus nigricans, Gloger Baryshnikov & Baranova 1983). The fossil material is (1835) synonymized the name with Cricetus cricetus, being taxonomically classified as M. raddei planicola misled by the black belly, which is characteristic of both Argyropulo, 1941 (Argyropulo 1941b). hamsters. Subsequent authors, starting with Giebel (1855), accepted Radde's hamster as a species in its own During the 2nd half of the 20th century, Radde’s golden right (Trouessart 1904, Argyropulo 1933b, c, Ellerman hamsters benefited from deforestation and expansion 1941, Vinogradov & Argyropulo 1941, Kuznetzov of agriculture (Tembotov 1972). On the other hand, 1944, Vinogradov & Gromov 1952, Flint et al. 1965). population decline and fragmentation have been This hamster was only exceptionally synonymized with reported since 2000 in Dagestan (Omarov & auratus (Ellerman & Morrison-Scott 1951, Yarovenko 2011, Chunkov 2018, 2020, Chunkov & Vereshchagin 1959). Some authors, however, Omarov 2020), Stavropol'skiy krai (Likhovid 2002, considered either brandti (Aharoni 1932, Vinogradov & Vasilenko et al. 2021, Tsapko et al. 2022), and Kalmykia Argyropulo 1941) or newtoni (Hamar & Schutowa 1961) (Sandzhiev et al. 2013). as a race of M. raddei. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 123. Figure 87: Distribution of Radde’s golden hamster Mesocricetus raddei. Radde’s golden hamsters occupy pristine cereal and buffy or rusty hair tips. Muzzle and face are lighter and wormwood steppe in flat landscape, high-mountain shaded buffy or rusty, though the crown is always grey xeric steppe, pastures and various types of cultivated or blackish. The cheek patch and the collar stripe are land. Some authors (Minoransky et al. 1997, Sandzhiev cream or greyish-white. The subauricular stripe is black et al. 2013) claim that uncultivated land is preferred and and the postero-lateral extension of sternal patch is that this hamster avoids proximity to humans (Ognev either absent or present (cf. Figures 81b, 88 & 89). The 1924, Shidlovsky 1962). Tembotov (1972) report its postauricular patch varies from being absent to an presence for Dagestan in the sub-Alpine zone up to extensive buffy-reddish spot; the crown patch and the 2,400 m high. Elevational range is from –23 m in the occipital stripe are usually bold though they are Caspian Depression to 2,565 m (mean = 826 m). occasionally absent. The sternal patch is large and black; the rest of the underside is usually blackish grey or Characteristics (Figure 81b & 88). A large hamster, black, though lighter than the sternal patch (Figure 90). second in size to C. cricetus. Dimensions: body mass = 200–350 g, length of head and body = 149–280 mm, The black area on the belly is occasionally narrowed to length of tail = 12–34 mm, length of hind foot = 19.0– a wide stripe. The area between the belly and lateral line 30.0 mm, length of ear = 14.2–31.0 mm; condylobasal is never pure black, but grizzled with beige hairs. Rarely, length of skull = 31.9–60.0 mm, zygomatic width = the entire belly is light-grey (similarly to the cheek patch; 17.2–28.0 mm, length of maxillary tooth-row = 6.2–8.6 Figure 90); in such cases, the demarcation on flanks is mm. Males are heavier than females; mean body mass distinct, though not sharp. Chin is either black or in M. r. raddei before hibernation is 296+12 g in males whitish, and the inguinal region is frequently distinctly and 248+9 g in females (Chunkov 2020). The fur is lighter than the belly. Exceptionally, a white spot is coarser and the overall colouration is darker than in the present also on the abdomen (M. M. Chunkov in litt.). remaining golden hamsters due to denser all-black hairs. Tail is grey and largely hidden by long hairs of the body; Colouration, however, varies individually and among paws are white to light-grey. The ears are sparsely clad populations. Dorsal fur is from plain grey to dull grey- with fine greyish or brownish hairs. brown; it is frequently heavily grizzled with black and 124 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. the condyles are therefore shifted further back. Apart from its large size, dentition shows no peculiarities (Figure 86). Two different diploid numbers have been reported for M. raddei, both from Chechen Republic: 2n = 42 from north-western (Vorontsov & Krjukova 1969c) and 2n = 44 from the southern parts of the country (Ivanov 1969a). Both cytotypes have identical fundamental number of chromosomal arms (NF = 76, NFa = 72). Figure 88: Radde’s golden hamsters from Dagestan (Mesocricetus raddei raddei). The bottom animal assumed aggressive defensive posture. Photo courtesy of A. V. Surov (top inset) and Yu. Yarovemko (bottom inset) Nipple count is 16 (K. Z. Omarov Figure 89: Flat skin of Radde’s golden hamster Mesocricetus raddei in litt .) and 19 (M. M. raddei from Kuli, Dagestan (SZM 23874). Chunkov in litt.). Glans penis is cylindrical, parallel- sided, quite deep, and with ventral groove; lateral The number of metacentrics is identical in both (5 papillae are expanded distally and Γ-shaped (Vorontsov elements); the 44 cytotype has 10 submetacentric and 6 1982). The baculum is short and robust, slightly wider acrocentric elements, while the 42 cytotype contains 11 basally than across the trident (Argyropulo 1933c). submetacentric and 4 acrocentric chromosomes (cf. Table 1 in Vorontsov & Krjukova 1969c). Both sex The skull is large and massive with a heavy rostrum chromosomes are metacentric; the X is the largest (Figure 85). Zygomatic width accounts for 54–60% of element in the karyotype and the Y is next in size to X condylobasal length of the skull. Nasals are longer than (Graphodatsky 2006b). in the remaining golden hamsters. In large individuals, the skull is heavily marked with ridges reaching the Variation and Subspecies. Nehring (1898c, d) powerful lambdoidal crest; they bent medially anterior classified raddei and nigriculus as independent species, to the fronto-parietal suture. The occipital region is which was accepted in first decades of the 20th century more inclined towards condyles than in congenerics; SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 125. Figure 90: Ventral side in Radde’s golden hamsters Mesocricetus raddei demonstrating variability in colouration. Mesocricetus raddei raddei (a–d) is from Dagestan and M. r. nigriculus (e–h) is from Rostov Oblast. (Satunin 1900, 1901, Dombrowski 1907, Heptner 1926, accepted here; they split 0.4–0.5 Mya (Neumann et al. Ognev & Heptner 1927) and is exceptionally still 2006). Fossil golden hamsters from Ciscaucasus are recognised (Hamar & Schutowa 1966, Gromov & usually classified as an extinct subspecies M. r. planicola Baranova 1981, Yiğit et al. 2006a). Argyropulo (1933b) Argyropulo, 1941 (Argyropulo, 1941b), which was of defined M. raddei as polytypic species with 3 subspecies intermediate size (Vereshchagin 1959, Gromov & (nigriculus and avaricus in addition to the nominotypical Baranova 1981). raddei), which received wide support (Sviridenko 1936, 1940, Heptner & Formozov 1941, Kuznetzov 1944, Mesocricetus raddei raddei Vinogradov & Gromov 1952, Shidlovskiy 1962, (Nehring, 1894) Gromov et al. 1963, Hamar & Schutowa 1966, Gromov subspecies, the larger Synonym: Mesocricetus raddei avaricus Ognev & Heptner, raddei & Baranova 1981). A prevailing view was of 2 and the smaller nigriculus 1927. (Heptner 1926, Ellerman 1941, Vinogradov 1933, Vinogradov & Argyropulo 1941, Vereshchagin 1959, Kuznetsov 1965, Ross 1992, Lebedev 2012, Kryštufek Distribution. South-western and southern Dagestan 2017b). These subspecies supposedly differ in diploid and central Chechnya (south of Grozny – Makhachkala Road), in the basins of rivers Samur, Argun, Andi number of chromosomes (2n = 44 in the nominotypical Koysu and Sulak, and on the plateaus of Khunzakh and raddei and 2n = 42 in nigriculus ; Vorontsov & Krjukova Gunib (Heptner & Formozov 1941, 1969c, Ross 1992); geographic ranges of the two Vereshchagin 1959, Chunkov 2020). cytotypes are actually little known. Two subspecies are 126 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Characteristics. Karyotype: 2n = 44. A large suture is long (Figure 94). The newtoni group contains 2 subspecies: length of head and body = 185–280 mm, species ( newtoni and brandti), which presumably diverged length of tail = 22–34 mm, length of hind foot = 24.2– at 1.7–1.8 Mya (Neumann et al. 2006). Fossil record 30.0 mm, length of ear = 20.0–31.0 mm; condylobasal allows tracing their history into the Middle Pleistocene; length of skull = 39.1–50.0 mm, zygomatic width = for newtoni see Santel & Koenigswald (1998) and for 19.6–28.0 mm, length of maxillary tooth-row = 7.8–8.6 brandti see Storch (1975) and Erdal et al. (2018). These mm. The underside, which is either light-grey or two golden hamsters are externally and cranially quite blackish-grey, is always lighter than the sternal patch similar and Hamar & Schutowa (1961) proposed for (Figures 81b, 89 & 90a–d). The skull is more robust and them to be conspecific. more heavily ridged; the rostrum is heavier and broader. Incisive foramina are frequently the widest in their Mesocricetus newtoni (Nehring, 1898) anterior part; the upper incisors are heavier. – Romanian Golden Hamster Mesocricetus raddei nigriculus Cricetus Newtoni Nehring, 1898b: 329. Type locality: “bei (Nehring, 1898) Schumla in Ostbulgarien [near Shumen in Eastern Bulgaria]”. Between 1950–1965, Shumen was Etymology. The epithet nigriculus is diminutive from renamed to Kolarovgrad (cf. Musser & Carleton ‘nigri’ (Latin adjective, inflection of ‘niger’ for black) in 2005: 1045). allusion to black underside of this hamster. Cricetus (Mesocricetus) Newtoni: Nehring, 1898d: 386. Name combination. Distribution. Lowlands (< 1,000 m of elevation) in Mesocricetus Newtoni: Nehring, 1899a: 1. First use of the Ciscaucasia, including northern Dagestan (Khasan- current name combination. Yurt; Sviridenko 1936, 1940). Throughout most of its Cricetus auratus newtoni: Vinogradov & Argyropulo, 1941: range, nigriculus is sympatric with C. cricetus. 167. Name combination. Mesocricetus auratus newtoni: Ellerman & Morrison-Scott, Characteristics. Karyotype: 2n = 42. A small 1951: 630. Name combination. subspecies: length of head and body = 149–186 mm, length of tail = 12–20 mm, length of hind foot = 19.0– Etymology. The species epithet is eponym for English 26.0 mm, length of ear = 14.2–24.0 mm; condylobasal zoologist Alfred Newton (1829–1907) who published length of skull = 31.9–42.3 mm, zygomatic width = (Newton 1870) the first record of Romanian hamster in 17.2–23.5 mm, length of maxillary tooth-row = 6.2–7.3 Europe under the name Cricetus nigricans Brandt (now mm. Underside tends to be darker and in some Mesocricetus raddei). The voucher, which is portrayed as individuals both the sternal patch and the rest of the colour plate XXVI in Newton’s paper, is deposited in underside are black (Figure 90e–h). The skull is more the Zoological Museum of the Cambridge University gracile and the ridges weaker or entirely absent; the (no. E 2373), where Newton was Professor of rostrum is weaker and narrower. Incisive foramina are Comparative Anatomy (1866–1907). Newton has wider in their posterior part; the upper incisors are eponyms in ornithology, which was his primary interest. weaker. Taxonomy. The first Romanian golden hamster ever Species group newtoni collected was classified as Cricetus nigricans Brandt (Newton 1870), but later on recognized as species in its The group is characterized by nucleotide sequences own right under the name newtoni (Nehring 1898b). (Neuman et al. 2006, Lebedev et al 2018a) and lower Shortly afterwards, newtoni was shifted to the genus diploid number of chromosomes (2n = 38–42). Glans Mesocricetus (Nehring 1899a), with this name penis is conical, narrowing from base towards the apex. combination remaining in use throughout the first half th of the 20 century (Trouessart 1904, Dombrowski Temporal ridges are weak and parallel, not reaching 1907, Miller 1912, Călinescu 1931a, b, Argyropulo beyond the fronto-parietal suture. The frontals are not 1933b, c, Ellerman 1941). Vinogradov & Argyropulo much compressed posteriorly and the fronto-parietal SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 127. (1941) and Ellerman & Morrison-Scott (1951) relegated Romanian hamsters occupy xerophilic grasslands and newtoni to a subspecies of auratus, which remained the fallow fields with perennial cereals, herbs and cruciferes prevailing view in the 1950s and 1960s (Petrov 1954, (Gavril et al. 2023). In the 1950s and 1960s, they were Popov 1955, Markov 1960, Ausländer & Hellwing relatively abundant, particularly in uncultivated land 1957, Hamar 1958, Atanassov & Peschev 1963). At (Petrov 1954, Zlatanov 1961). This is a lowland species, about the same time, Hamar & Schutowa (1961) occupying elevations from close to sea level (minimum synonymized newtoni with brandti of Asia Minor, a step = 4 m a. s. l.) up to 467 m in the Măcin Mts. (Tulcea which did not receive support. Species status for newtoni County, Romania; Hamar & Schutowa 1966); mean was reinstated by Raicu & Bratosin (1966) on the basis elevation is 135 m. of its unique karyotype (2n = 38). Characteristics (Figures 81d & 92). Size is Distribution. The range covers an area of 37,710 km2 approximately as in auratus and brandti. Dimensions: in south-eastern Romania and Bulgaria (Figure 91). It body mass = 60–130 g, length of head and body = 135– stretches along the Black Sea Coast (from Dobrogea as 160 mm, length of tail = 18–26 mm, length of hind foot far south as northern Burgas) and along the right bank = 15–22 mm, length of ear = 14–20 mm; condylobasal of the Danube River as far west as the districts of length of skull = 32.0–38.2 mm, zygomatic width = Montana and Vratsa (Bulgaria). All the records are to 18.0–21.2 mm, length of maxillary tooth-row = 6.0–8.8 the south of Danube (Hamar & Schutowa 1966, mm. Romanian hamsters are characterized by Murariu & Stanciu 2009). Contrary to some earlier colouration and a rat-like head with more pointed snout reports (e.g. Ross 1992), this species does not occur in than in other golden hamsters (Lyman & O’Brien Ukraine. During the Late Pleistocene, the range 1977). Dorsal fur varies from light drab-brown to encompassed parts of Serbia and Greece and the blackish-grey and is usually inconspicuously speckled species also occupied high elevations, where it is not with blackish hairs. Underparts are light greyish with present any longer (summarized in Peshev et al. 2004). cream, buffy or blackish shades (Figure 93). In the Nedyalkov et al. (2015) reported on 2 translocations in extreme the underside is as dark as in M. raddei. The Bulgaria (Sofia and Kazanlak) outside the current range. sternal patch is blackish-brown or pure black and more extensive than in other golden hamsters; its length is Figure 91: Distribution of Romanian golden hamster Mesocricetus newtoni. 128 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 92: Romanian golden hamster (Mesocricetus newtoni) from Dobrogea, Romania. Photo courtesy of Gabriel Chişamera. Figure 93: Ventral side of Romanian golden hamsters Mesocricetus newtoni demonstrating variability in sternal patch. ~50 mm. Approximately ½ of skins we saw showed an Usually, the crown continues posteriorly as a stripe additional blackish patch in the inguinal region. White which reaches the scapular region or extend even patches, either in the chin or the inguinal part, or both, beyond (Figures 81d & 92). The face and the are rarely present (Figure 93). A blackish crown patch postauricular patch are beige-brown or bright buffy- is well marked and larger than in other golden hamsters. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 129. Figure 94: Skull in golden hamsters from the newtoni species species group (top to bottom): Mesocricetus newtoni and M. brandti (Kırşehir, Central Anatolia). Scale bar = 5 mm. Figure 95: Grinding pattern of upper (a, b, c) and lower (a’, b’, c’) molars in the newtoni species group of golden hamsters: a, b – Mesocricetus newtoni, c – M. brandti. m – mesolophid. Scale bar = 1 mm. 130 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. brown; the cheek patch and the collar stripe are cream. Cricetus (Mesocricetus) Brandti: Nehring, 1898d: 383. The subauricular stripe is bold and black; the light collar Name combination. stipe is posteriorly frequently margined by a black M[esocricetus] brandti: Satunin, 1900: 301. First use of the postero-lateral expansion of the sternal patch. The tail current name combination. and paws are whitish and the ears are grey. Females Mesocricetus Koenigi Satunin, 1900: 301. Type locality: have 13–16 nipples (Miller 1912, Niethammer 1982). “Kasikoporan (Gouvt. Eriwan)”, now Göle, Villayet Gland penis and baculum were not studied. The skull is Ardahan, Turkey. Ellerman (1941: 464) mistakenly comparatively weekly ridged (Figure 94). Zygomatic stated Nehring as the taxonomic authority for width accounts for 53–59% of condylobasal length; in koenigi, which is followed in the mainstream dorsal view, the zygomatic ridges converge anteriorly. literature (e.g. Ellerman & Morrison-Scott 1951, Dentition shows no peculiarities (Figure 95a, b). Corbet 1978, Pavlinov & Rossolimo 1987, Musser & Carleton 1993, 2005). Karyotype: 2n = 38, NF = 76; all the chromosomes are [Cricetus (Mesocricetus)] koenigi: Trouessart, 1904: 394. bi-armed. Sex chromosomes are bi-armed and large; the Name combination. X is one of the largest elements (Popescu & DiPaolo Cricetus (Mesocricetus) raddei brandti: Aharoni, 1932: 172. 1980). Name combination. Cr[icetus] (Mesocricetus) auratus brandti: Argyropulo, Variation and subspecies. Monotypic (Kryštufek 1933b: 244. Name combination. 2017d). Cricetus auratus brandti: Vinogradov & Argyropulo, 1941: 167. Name combination. Mesocricetus brandti (Nehring, 1898) – M[esocricetus] auratus brandti: Kuznetzov, 1944: 323. Brandt’s Golden Hamster Name combination. M[esocricetus] a[uratus] koenigi: Kuznetzov, 1944: 323. Cricetus Brandti Nehring, 1898b: 331. Based on Mesocricetus brandt Name combination. : Vorontsov, 1958: 334. Incorrect “transcaucasischen Exemplare”. Of the 3 syntypes subsequent spelling of brandti Nehring. cited in a subsequent paper (Nehring 1898d: 384), only 1 has known locality (“Marienfeld, östlich von The species epithet is eponym for Russian Etymology. Tiflis“), which Ellerman (1941: 444) accepted as a naturalist of German ethnicity Johann Friedrich von restricted type locality (“Gouv. Tiflis, Brandt; in Russian Fedor Fedorovich Brandt ( Фёдор Transcaucasia”), i. e. Tbilisi, Georgia. Фёдорович Брандт or Иоганн Фридрих фон Figure 96: Distribution of Brandt’s golden hamster Mesocricetus brandti. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 131. Брандт) (1802–1879), the first director of the 494,197 km2 in south-western Asia (Figure 96). It is split Zoological Museum of St. Petersburg Academy of by the main ridge of the Caucasus Mts. into two Sciences. Brandt has eponyms also in other branches of fragments, the southern (Turkey, Iran, Armenia, natural history. Azerbaijan, Georgia) and the northern in Dagestan (Russian Federation). Earlier reports for northern Iraq, Taxonomy. Brandt’s golden hamster was originally Syria, Lebanon, and northern Israel (Musser & reported for ‘Assyria’ as Cricetus vulgaris (Ainsworth Carleton, 2005) are erroneous (Shehab et al. 2004, 1838: 39) and for Mersin, Turkey, as a species “identical Kryštufek & Vohralík 2009). In Turkey, M. brandti with our European species” (Kotschy 1858: 234; occupies central and eastern Anatolia, to the east of the interpreted as Cricetus frumentarius in Danford & Alston Çardak (Denizli) – Uşak line, and the eastern Black Sea 1877: 280). Subsequent reports were as Cricetus nigricans Mts. It is marginally present in the Taurus Mts. (now Mesocricetus raddei) for Iran (Filippi 1865) and Asia (Kryštufek & Vohralík 2009). In Iran, the range is Minor (Danford & Alston 1877, 1880). The opinion restricted to the north-western part of the country, with that Brandt’s golden hamster is a subspecies of M. raddei the border crossing the following provinces (north-west was still advocated by Aharoni (1932). After being to south-east): Mazanderan, Tehran, Qazvin, Hamadan, separated from the scope of raddei as a species in its own Kordestan, and Kermanshah (Missone 1959, Yusefi et right (Nehring 1898b), brandti was rarely treated as an al. 2019). The rest of the Transcaucasian range independent species (Trouessart 1904, Satunin 1906, tentatively coincides with the Lesser Caucasus (east of Dombrowski 1907, Vinogradov 1933), being usually Arskiansk and Suramsk ridges), and Talysh ranked as a subspecies of auratus (Argyropulo 1933b, c, (Vereschchagin 1959, Shidlovskiy 1962, Omarov & Neuhäuser 1936, Ellerman 1941, 1948, Ellerman & Chunkov 2020). Within this frame, the Brandt’s Morrison-Scott, 1951, Vinogradov & Gromov 1952, hamster is widespread in Armenia (Dal’ 1954), and Dal’ 1954). Although karyotypes for both, auratus and occupies western Azerbaijan and south-central brandti, were known already in the early 1950s (Matthey Georgia, as far north as the Caucasian main ridge, and 1952) and hybridization tests demonstrated their as far west as the coastal lowlands in Imereti, Guria, and reproductive incompatibility (Matthey 1959), many Samegrelo-Zemo Svaneti (Bukhnikashvili 2004). The authors continued pooling these taxa well into the isolate in Dagestan is bordered by the Sulak and 1990s (Osborn 1965, Lay 1967, Sickenberg 1971, Gimrinskiy ridges in the north and west, respectively Atallah 1977, Corbet 1978, Harrison & Bates 1991, (Shidlovskiy 1962), and encompasses the Levashinskiy Qumsiyeh 1996). On the other hand, the evidence Plateau in the territory of 5 Rayons: Buynakskiy, quoted above, followed by generic revision by Hamar Levashinskiy, Akushinskiy, Sergokalinskiy, and & Schutowa (1966) convinced many to accept species Karabudahkentskiy (Omarov & Yarovenko 2011, status for brandti (Missone 1959, Tembotov 1965, 1972, Omarov & Chunkov 2020). Brandt’s hamsters are Lehmann 1969, Zil’fyan et al. 1969, Shidlovskiy 1962, rarely present on the seashore ( e. g. along the Black Sea Kumerloeve 1975, Storch 1975, Lyman & O’Brien coast of Turkey) and do not occupy islands. 1977, Kittel 1984, and all subsequent authors). In the past, brandti was exceptionally synonymized with newtoni The range was seemingly more extensive in the Upper (Hamar & Schutowa 1966, Kurashvili et al. 1981). Pleistocene when Mesocricetus cf. brandti was present also in northeastern Iraq (Palegawra Cave, 14,400 ±760 Mesocricetus koenigi was recognized in the 1900s as a years old and identified as M. cf. armatus) (Turnbull species distinct from M. brandti on the basis of fur 1975) and Lorestan (Iran; Rey-Rodríguez et al. 2020). colouration. Its validity was accepted only occasionally (Trouessart 1904, Dombrowski 1907, Vereshchagin Its main habitat consists of dry Artemisia and Festuca 1959) and the name was soon synonymized with brandti steppe with abundance of cereal grasses; Brandt's by the majority of authors. hamsters are regularly present in the fields of cereals and multi-annual crops. Woodland, thickets, damp and Distribution. The range of Brandt’s hamster is by far desertified places are avoided. The range is contiguous the most extensive in the genus and covers an area of in subalpine meadows but patchy in places of 132 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 97: Brandt’s golden hamster (Mesocricetus brandti) from Turkey. Photo courtesy of Christian Kern. Used with permission of the Science and Research Centre Koper. pronounced aridity where hamsters aggregate in mesic prominent than in auratus but smaller than in newtoni. sites and in river valleys. Elevational range is 37–3,365 The patch is blackish-brown or black; it is frequently m (mean = 1,382 m) with the majority of records surrounded by white patches and split medially. The between 1,100 and 2,200 m a. s. l. (Kryštufek & oblique black subauricular stripe extends from cheeks Vohralík 2009). to shoulders and is usually bold blackish-brown or black; in rare cases, the stripe is narrow and ill-defined. Characteristics (Figures 81c & 97). Size is similar as in The postero-lateral extension of sternal patch is absent M. auratus and M. newtoni. Dimensions: body mass = or ill-defined; it is never as bold as in newtoni. Light 81–271 g, length of head and body = 135–166 mm, patches on chin, neck and cheeks (the cheek and length of tail = 10–27 mm, length of hind foot = 17.5– postauricular patches and the collar stripe) are cream or 22.0 mm, length of ear = 17.5–24.0 mm; condylobasal yellowish. Head is normally buffier than the back, and length of skull = 31.1–38.2 mm, zygomatic width = some individuals show a dark line across masseters. A 17.6–21.4 mm, length of maxillary tooth-row = 5.9–7.0 dark crown patch is usually present but never as bold mm. Dorsal pelage is sand-brown to tawny-olive; on and prominent as in newtoni; the occipital stripe is average, it is less grey than in newtoni and raddei and absent. Fore feet are yellowish; hind feet are grey and never as richly reddish as in auratus (Figure 81). In some covered by short buff hair. Ears are grey, covered by individuals, the shoulders are more blackish and the buff hair. Tail is whitish or yellowish at the tip. rump rustier. Flanks are yellowish and demarcation line is indistinct. Belly is grey-white to white, invariably Females have 8 pairs of nipples. Glans penis resumes washed with slate grey undercolour. Chin and throat are shape of a broad truncated cone; it is wider than deep. frequently white and some animals have white patches The ventral groove is restricted to the proximal part of or / and white medial line on the belly (Figure 98a). The the glans (Vorontsov 1982). Baculum is essentially like sternal patch (length = 29–34 mm) is larger and more in M. auratus, except being larger and less expanded in SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 133. Figure 98: Ventral side of Brandt's golden hamsters Mesocricetus brandti demonstrating variability in sternal patch: a–c, h – Anatolia; d – Iran; f, g – Azerbaijan. its medial part; its distal portion is longer relative to studied throughout the range, specifically in Turkey, proximal stalk (Yiğit et al. 2000). The entire baculum is Iran, Armenia, Georgia and Dagestan (Ivanov 1969a, about 5.5 mm long, 2 mm wide across its basal shaft Zil’fyan et al. 1969, Todd et al. 1972, Lyman & O’Brien and 1.6 mm across distal processes (Kryštufek & 1977, Popescu & Di Paolo 1980, Doğramacı et al. 1994, Vohralík 2009). Yiğit et al. 2006b, Aşan 2012, Arslan & Zima 2014, Çam et al. 2015). The individual descriptions may differ in The skull is essentially as in M. newtoni (Figure 94). evaluation of the centromere position in two smaller Zygomatic width accounts for 52.4–58.2% of pairs of autosomes (acrocentric or biarmed), which condylobasal length of the skull. Pterygoids tend to be resulted in different fundamental numbers (NFa = 76, parallel and join orthogonally the posterior margin of 78, 80, NF = 80, 82, 84). Hamsters with different NFa the hard palate. Interpterygoid fossa is thus mainly hybridized in captivity and hybrids have intermediate rectangular, though some individuals show triangular NF (Çam et al. 2015). Additionally, Popescu & Di Paolo fossa. Masseteric plate is slightly longer (length = ~ 3 (1980) reported 2n = 44 (NFa = 80) in hamsters from mm) than in M. auratus (~ 2.0 mm), and infraorbital Ankara, presumably a result of Robertsonian foramen is laterally compressed (Figure 20b), while it is rearrangement (Arslan & Zima 2014); this observation oval in auratus. Dentition shows no peculiarities (Figure remains unconfirmed. Romanenko et al. (2007) 95c). retrieved 1 heteromorphic autosomal pair (chromosome 18), consisting of 1 metacentric and 1 Karyotype: 2n = 42, NFa = 80, NF = 84; sex acrocentric chromosome, which gave odd number of chromosomes are bi-armed, X is medium-sized or large chromosomal arms NFa = 77. and Y is of medium size or small. Karyotype was 134 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Variation and subspecies. Various authors reported O’Brien 1977, Yiğit et al. 2000, 2006b, Kryštufek & interpopulation variation in size and fur colour; Vohralík 2009). Vereschagin (1959) classified Brandt’s chromosomal variation is seemingly irrelevant for hamsters from the Greater Caucasus as koenigi and subspecific taxonomy. Brandt’s hamsters are smaller in those from the Lesser Caucasus as brandti. The the western part of their range (central and eastern remaining authors made no attempt to use trinomials Anatolia), large in Iran and of intermediate size in for categorizing geographic variation. Subsprecific north-eastern Anatolia, where they are also the darkest. taxonomy in Brandt’s golden hamster remains a task for Pale fur is characteristic for populations occupying the the future (Kryštufek 2017c). extreme eastern Anatolia (Van) and Iran (Lyman & TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot TRIBE: Urocricetini – New Tribe Taxonomy. In the past, Urocricetus and Phodopus s. lato coli in Urocricetus and Cricetiscus, which is subdivided into were never classified into the same family-group taxon 3 segments in Phodopus (Vorontsov 1967). (5) The below the level of Cricetinae. Some authors (Ellerman central digit of the trident is short and rounded (known 1941, Ellerman & Morrison-Scott 1951) stressed, only in Phodopina new subtribe), while it is usually long however, small and flattened bullae shared by these and narrow in the rest of true hamsters (Figure 17). (6) genera that separate them from all other true hamsters. Diploid number of chromosomes (2n = 28–34) is Cladistic analysis of Cricetinae conducted by Ross intermediate between Cricetini (2n = 20–28) and (1992) further showed that Urocricetus and Phodopus s. lato Mesocricetini (2n = 38–44). were sister taxa, occupying basal position in the subfamily. This was subsequently confirmed in Content. The new tribe contains 3 genera (Urocricetus morphological study based on the structure of auditory Satunin, 1902, Phodopus Miller, 1910, Cricetiscus Thomas, bullae (Potapova 2005) and in phylogenetic studies 1917) with 5 recent species. These genera are classified using chromosomal data (Romanenko et al. 2007) and in 2 subtribes: Urocricetina and Phodopina new molecular markers (Lebedev et al. 2018a) (Figure 1). subtribe which split at approximately 9.2–10.1 Mya, i. e. Time of evolutionary divergence of Urocricetini v. during the early Late Miocene (Romanenko et al. 2021). Cricetini + Mesocricetini was estimated at 12.25 Mya (95% CI = 10.24–14.54 Mya) (Lebedev et al. 2018a). Distribution. Southern Siberia in Russia, north-eastern Urocricetini new tribe is well diagnosed by a set of and eastern Kazakhstan, Mongolia, northern China, morphological, chromosomal and molecular data. Tsaidam Depression and the plateaus of Ordos and Tibet in China, northern Nepal and north-western Type genus. India. The two subtribes, Urocricetina and Phodopina, Urocricetus Satunin, 1902. are largely allopatric, although their ranges are locally in Diagnosis and Comparisons. contacts along the northern border of Tibet (Figure Urocricetini new tribe belong to Cricetinae, as evident from their morphology 100). (e. g. bicuspidate dentition and the presence of inner cheek pouches) and phylogenetic analyses based on nucleotide sequences (Steppan & Schenk 2017, Lebedev et al. 2018a). On the other hand, Urocricetini differ from remaining tribes of Cricetinae, i. e. Cricetini and Mesocricetini, in nucleotide sequences and in a set of morphological and chromosomal data. In Urocricetini, (1) the plantar surface is partly (Figure 101) or completely furry (Figure 109), while hairs are present only posterior to metatarsal pads in the Figure 99: Right bulla in ventral view in Urocricetus lama alticola (a) remaining Cricetinae (Figures 33 & 80). (2) Bony and Nothocricetulus migratorius (b). Mesial is to the right, anterior is at eustachian tube is elongated (Figure 99a), but is short in the top. Not to scale. Abbreviations: abt – auditory bullar tube (bony other true hamsters (Figure 99b). (3) Corneous eustachian tube); am – auditory meatus; bo – basioccipital bone; cc epithelium of the stomach extends along border of – carotid canal; eab – ectotympanic part of auditory bulla; flp – ; flm – foramen lacerum posterior foramen lacerum medius ( fissura isthmus and may occupy most of the glandular region petrotympanica ); mp – mastoid process; ppb – petrosal part of bulla; while it is mainly restricted to the forestomach in the ppe – processus pterygoideus externus ; sf – stapedial foramen. remaining Cricetinae (Figure 15). (4) There is 1 ampulla 136 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 100: Distributional ranges of the Urocricetini subtribes, Urocricetina (green) and Phodopina (red). Zones of contact between these subtribes are pointed by arrows. SUBTRIBE: Urocricetina – New Rank Type genus. Urocricetus Satunin, 1902. Diagnosis and Comparisons. Urocricetina differ from Phodopina new subtribe in nucleotide sequences (Lebedev et al. 2018a, Romanenko et al. 2021) and in a set of morphological and chromosomal data. In Left palm in Figure 101: Urocricetus lama. Digits are indicated by Urocricetina, (1) the plantar surface is only partly hairy Roman numerals (I = thumb); medial and lateral interdigital pads between the pads (Figure 101), but completely furry in are indicated by Arabic numerals (1 and 4, respectively); ML – lateral Phodopina (Figure 109); (2) there are 6 plantar pads (1 metatarsal pad, MM – medial metatarsal pad. or 3 pads in Phodopina); (3) the tail is long (> 30% of head and body length), while it is vestigial in Phodopina Genus: Urocricetus Satunin, 1902 – (shorter than 20% of head and body length); (4) the Tibetan hamsters corneous epithelium of the stomach extends along the region as is the case in Phodopina; (5) the sphenofrontal & Morrison-Scott 1951: 624; border of isthmus, but does not occupy most glandular Urocricetus Satunin, 1902: 573. Not 1903 (e.g. Ellerman foramen is present (absent in Phodopina) (the foramen 395). Type species: cf. Trouessart 1904: is situated on the fronto-sphenoidal suture and can be monotypy). Urocricetus kamensis Satunin (by seen on the ventral side of the skull). Content. Urocricetus meaning ‘-tailed’ (from Greek ‘oura’, Urocricetina contain a single genus Etymology. The name is a composite of ‘ouros’ i. e. ‘tail’) and with 2 recent species. Cricetus for a hamster (see the Etymology under Cricetus ), therefore ‘a (long)tailed hamster’. Satunin (1902) coined the name for a group of small hamsters, classified in SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 137. Cricetulus, which had proportionally long tails: Urocricetus older ( c. 3.93 Mya) being triggered by the formation of kamensis, Cricetulus longicaudatus and Tscherskia triton. the Mekong-Salween Divide in the early Pliocene. Taxonomy. Satunin (1902) established Urocricetus as a Distribution. The range is encircling the Tibetan subgenus of Cricetulus (thought used it as a full generic Plateau in China (southern Xinjiang, southern Gansu, name) for the sole long-tailed small grey hamster in south-eastern Qinghai and adjacent Sichuan, and Kozlov’s collection from China (U. kamensis). In southern Xizang), northern Nepal and north-western Satunin’s (l. c.) view, the new subgenus encompassed India (Uttaranchal, and Jammu and Kashmir). The 2 further 2 long-tailed members of Cricetulus s. lato, species of Tibetan hamsters are allopatric, while the specifically Cricetulus longicaudatus and Tscherskia triton. genus is parapatric with respect to Phodopina (Figure Trouessart (1904) still acknowledged Urocricetus as a 100). valid subgenus of Cricetus, however, Argyropulo (1933b, c) synonymized it with the subgenus Cricetulus. By then, all species-group taxa of the current Urocricetus have already been named (lama, alticola, and tibetanus) and they were all classified as Cricetulus. True identities of these taxa and their interrelationships remained controversial. Ellerman (1941) classified these taxa into different groups within Cricetulus; taxa represented in London kamensis Figure 102: Carded skin of Urocricetus lama alticola (from Menshi, was in the longicaudatus group. Wang & Cheng Xizang, China) in dorsal view. Note a dorsad expansion of white (1973) showed close taxonomic links between (lama, alticola, and tibetanus) were in the lama group, while kamensis, ventral fur posterior to the rib cage and at the inguinal region, which lama and tibetanus, though still keeping them in Cricetulus. is due to undulating lateral line. The current scope of Urocricetus was finally set by Ross (1992); her results, however, were overlooked and Characteristics. Small and long-tailed hamsters Urocricetus remained for the next three decades in a (Figures 102, 106 & 108), which are externally most synonymy of Cricetulus (Huang et al. 2008, Musser & similar to Nothocricetulus migratorius and Cricetulus Carleton 1993, 2005, Zhang et al. 1997, Smith & longicaudatus, yet they are of smaller size. Some authors Hoffmann 2008, Hu et al. 2014, Kang et al. 2016, Jiang stressed the external similarity between Tibetan et al. 2015, Ding et al. 2016b, Pardiñas et al. 2017, Ding hamsters and mountain voles (Alticola argentatus and A. & Liao 2019). Generic status of Urocricetus was at last staliczkanus) (e. g. Thomas 1917, Lim & Ross 1992). Fur restored by Lebedev et al. (2018a). is soft, dense and moderately long (length = 9.5–11 mm) with longer sparse hairs protruding by 2.5–3 mm. Corbet (1978) proposed a 2-species solution for Mystacial vibrissae measure 33–37 mm. Ears are large Urocricetus with a polytypic kamensis and monotypic (as long as hind foot), rounded and sparsely clad with alticola. This arrangement remained largely unaltered for short hairs. Tail is moderately long, thick, and densely the next 4 decades. Scope of the polytypic kamensis was covered by hair, which usually conceals the underlying defined already by Wang & Cheng (1973), and included annulation; the terminal pencil is long (length = 4–7 lama and tibetanus. Phylogenetic analysis by Ding & Liao mm). Feet have 5 plantar and 6 palmar pads; interdigital (2019) showed, however, that lama and tibetanus align plantar pads 2 and 3 are distinctly small, while the with alticola, which necessities nomenclatural and remaining pads (pads 1 and 4) are large and of same taxonomic changes. We therefore recognize a size. Plantar surface is largely nude, though there are monotypic kamensis and polytypic lama (with alticola and some hairs between the pads (Figure 101); palms are tibetanus). The 2 species presumably diverged in the nude. Claws are less robust than in the remaining Early Pleistocene at about 1.73 Mya (95% CI = 1.46– hamsters; they are whitish or cream. The front thumb 2.03 Mya; Ding & Liao 2019) or 0.94 Mya (95% CI = is rudimentary but with distinct claw. Dorsal fur varies 0.02−1.89 Mya; Lebedev et al. 2018a). In the estimate between pale fulvous-grey and dull-brown; it is grizzled by Pan et al. (2024), the evolutionary split is significantly by black hairs which are more numerous on the crown 138 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 103: Skulls in Tibetan hamsters; top – Urocricetus lama (Dzakar Chu, Xizang, China); bottom – U. kamensis (Qinghai, north- eastern Tibet, China). of the head and on the posterior back. Hairs on the belly comparatively narrow; zygomatic width accounts for have slate bases and white tips; demarcation line is clear 53.9–58.8% of condylobasal length. Occipital condyles and wavy. White underside makes a deep salient are not visible in dorsal view. Rostrum is moderately posterior to the rib cage (Figure 102); there are further long and braincase is large; nasals are long and the nasal 2 shallower salient angles on the cheeks and in the process of the premaxillary does not reach far beyond inguinal region. Ears are grey and frequently white the naso-maxillary suture. Frontals, parietals and margined; feet are white. Females have 4 pairs of occipitals are not ridged. Interorbital constriction is nipples (2 pectoral and 2 inguinal pairs). Glans penis wide; interparietal bone is not restrained but expands and baculum have not been studied yet. across the entire roof of the skull. The masseteric plate is relatively small with the anterior margin inclined Skull (Figure 103) closely resembles condition in backward; viewed in dorsal profile, the zygomatic spine Cricetulus and Nothocricetulus in size and proportions. It is is weak and the notch is shallow. Incisive foramens are SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 139. long and wide; posteriorly, they nearly reach the M1 Kham is one of 3 traditional Tibetan regions in which level. The palate terminates at the posterior margin of the type specimen has been collected. M3. The bullae are small (length = 3.9–5.0 mm) and flat, with large bony eustachian tube at their anteromedial portion. Mandible is shallow; the coronoid process is short and blunt. The upper incisors tend towards the opisthodont condition; molars are decidedly shorter than the incisive foramina. The 1st and 2nd internal folds (if1 and if2) are contiguous with the 1st and 2nd primary folds (pf1 and pf2) on M1 (Figure 104). Diploid number of chromosomes is 30 (known only in U. kamensis). Key to species 1a) Tail longer (> 50% of length of head and body), sharply bicolour, blackish above; present in Qinghui and Sichuan, and along the northern and eastern edges of the Tibetan Plateau Figure 104: Grinding pattern of upper (a, b) and lower (a’, b’) ……………………….………......…… kamensis molars in (a) Urocricetus lama lama (Tingri, Xizang, China) and (b) U. 1b) Tail shorter (< 50% of length of head and body), l. alticola (Ladak, Jammu and Kashmir, India). Abbreviations: if1, if2 indistinctly bi-colour or entirely white; present – internal folds 1 and 2, respectively; pf1, pf2 – primary folds 1 and along the southern and western edges of Tibetan 2, respectively. Scale bar = 1 mm. Plateau ………………………….....………. lama Although Satunin’s Tibetan hamster was Taxonomy. Urocricetus kamensis nearly uniformly classified as a species in its own right, Satunin, 1902 – its taxonomic status was uncertain (Corbet 1978); Satunin’s Tibetan hamster Ellerman & Morrison-Scott (1951) commented on kamensis as being nomen dubium. In a revision of Chinese Urocricetus kamensis Satunin, 1902: 574. Type locality: Tibetan hamsters (Wang & Cheng 1973), C. kamensis “Fluss Mok-tschjun im Gebiete des Mekong”, “im was defined as a polytypic species with 4 subspecies (the Lande Kam (die locale Benennung N.-O. -Tibets)”. nominotypical, lama, tibetanus and kozlovi); note that Ellerman (1941: 433) spelled the type locality as kozlovi is currently in the synonymy of Nothocricetulus “River Mok-tschjun [Moktschjun in Ellerman & migratorius. Wang & Cheng (l. c.) extracted kamensis from Morrison-Scott 1951: 625], district of Mekong, the scope of Cricetulus longicaudatus, where allocated by North-Eastern Tibet”. In current transcription, the Flint (1966b) and retained until very recently (Honacki locality is the Mokchu River, a tributary of the et al. 1982, Musser & Carleton 1993, 2005, Zhang et al. Yuchu in the Mekong Basin; Province of Qinghai, 1997, Luo et al. 2000, Wang 2003, Huang et al. 2008, north-eastern Tibet, China. Smith & Hoffmann 2008, Hu et al. 2014, Jiang et al. [Cricetus (Urocricetulus)] kamensis: Trouessart, 1904: 395. 2015, Pardiñas et al. 2017, Burgin et al. 2020, Name combination. Romanenko et al. 2021). Evidence for a monotypic Cr[cetulus] (Cricetulus) kamensis: Argyropulo, 1933b: 246. scope of kamensis and a shift of lama and tibetanus into Name combination. synonymy of alticola was provided by Romanenko et al. U[rocricetus] camensis: Werth, 1934: 212. Incorrect (2021). subsequent spelling of kamensis Satunin. [Cricetulus longicaudatus] kamensis: Flint, 1966b: 14. Name Distribution. The range outspreads across an combination. estimated 103,775 km2 of mountainous landscape in central and south-central China and centres in the Etymology. The species epithet is derived from Hengduan Mts. in the Three Rivers Source Region ‘Kham’ with the addition of adjectival suffix '-ensis'. (Sanjiangyuan) (Figure 105). The majority of records are 140 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 105: Distributional range of Satunin’s Tibetan hamster Urocricetus kamensis. from the upper Yangtze and Mekong Rivers in (eastern Qinghai), the Qilian Mts. (southern Gansu), southern Qinghai; the range stretches further south into and in the Altun Shan Mts. (south-eastern Xinjiang). north-western Sichuan and encompasses the extreme Satunin’s Tibetan hamster occupies thickets, grasslands south-eastern Xizang. There are at least 3 isolates to the and cultivations, but prefers valleys with goosefoot and north of the Yangtze River in the Qaidam Basin legumes; readily enters human dwellings (Zheng 1986, Figure 106: Satunin’s Tibetan hamster Urocricetus kamensis from Xizang, China. Photo courtesy of A. V. Surov. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 141. Luo et al. 2000). Elevational range is 2,485–4,630 m Cr[icetulus] (Cricetulus) lama lama: Argyropulo, 1933b: (mean = 3,925 m); Zheng (1986) reports it as high as 247. Name combination. 5,150 m. Cr[icetulus] (Cricetulus) lama alticola: Argyropulo, 1933b: 247. Name combination. Characteristics. A long-tailed species (Figure 106); Cr[icetulus] (Cricetulus) tibetanus: Argyropulo, 1933b: 247. length of tail accounts for 50–75% of length of head Name combination. and body. Dimensions: body mass = 21–42 g, length of Cricetulus alticola alticola: Ellerman, 1947: 361. Name head and body = 80–112 mm, length of tail = 48–64 combination. mm, length of hind foot = 17–20 mm, length of ear = C[ricetulus] kamensis lama: Wang & Cheng, 1973: 64. 16–18 mm; condylobasal length of skull = 23.5–26.3 Name combination. mm, zygomatic width = 13.2–14.8 mm, length of Cricetulus kamensis alticola: Zheng, 1986: 374. New rank maxillary tooth-row = 3.9–4.2 mm. Dorsal colour is and name combination. greyish buff to greyish brown with no decided yellowish Urocricetus k[amensis] lama: Ross, 1992: 197. Name or russet tinge, noticeably clouded with an admixture of combination. blackish hair tips that may form a fuzzy spinal stripe. Urocricetus alticola: Ross, 1992: 197. Name combination. The head and ears are grey. Ventral side is white and U[rocricetus] a[lticola] alticola: Romanenko, Lebedev, clouded by slate hair bases; chin is white to hair bases. Bannikova, Pavlova, Serdyukova, Feoktistova, Qu, Demarcation line is sharp. The tail is sharply bicolour, Sun, Surov & Graphodatsky, 2021: not paginated. dark brown or blackish above and creamy below; Name combination. terminal pencil is pure white (Figure 106). Skull and U[rocricetus] a[lticola] lama: Romanenko, Lebedev, dentition as for the genus (Figures 103). Bannikova, Pavlova, Serdyukova, Feoktistova, Qu, Sun, Surov & Graphodatsky, 2021: not paginated. Karyotype: 2n = 30, NFa = 50; the autosomal set Name combination. contains 11 pairs of biarmed chromosomes and 3 pairs U[rocricetus] a[lticola] tibetanus: Romanenko, Lebedev, of acrocentrics; both sex chromosomes are acrocentric; Bannikova, Pavlova, Serdyukova, Feoktistova, Qu, the X chromosome is of medium size and the Y Sun, Surov & Graphodatsky, 2021: not paginated. chromosome is the smallest element. The karyotype has Name combination. 38 autosomal conserved segments, which is more than U[rocricetus] lama: Pan, Wang, Liu, Li, Liao, Chen, Peng, in any other representative of Cricetinae (Romanenko Zhu, Li & Liu, 2024: not paginated. First use of the et al. 2021). current name combination. U[rocricetus] a[lticola] tibetanus: Pan, Wang, Liu, Li, Liao, Variation and subspecies. Monotypic. Chen, Peng, Zhu, Li & Liu, 2024: not paginated. Name combination Urocricetus lama (Bonhote, 1905) – Ladak Tibetan Hamster Etymology. Bonhote (1905a, b) did not explain the etymology of the species epithet lama which, in any case, Cricetulus lama Bonhote, 1905a: 14. The emended in allusion to Dalai Lama, the title of the foremost was common practice in his time. The name is probably description and the type locality (“Lhasa, Tibet”) spiritual leader of one of the leading schools of Tibetan were reported subsequently (Bonhote 1905b: 304– Buddhism. Until 1951, the Dalai Lamas headed the 305). Tibetan Government in Lhasa, which is also the type Cricetulus alticola Thomas, 1917: 455. Type locality: locality of Bonhote’s Cricetulus lama. ‘Lama’ (bla-ma) is “Shushal [Shushul; Ellerman 1941: 433], 13.500’ Tibetan for ‘master, guru’. Bonhote (1905b: 304) [4,115 m]”, Ladak, Jammu and Kashmir, India. believed that U. lama was identical to “the little white Cricetulus alticola tibetanus Thomas & Hinton, 1922: 180. mouse” reported by Walton (1905: 423) for the Jo-kang Type locality: “Tingri, Tibet 14,000’ [4,267 m]”, Shrine in Lhasa. Although Walton ( l. c .) remarked that Xizang, China. these rodents “belong to the species of the ordinary Cr[icetulus] (Cricetulus) lama: Argyropulo, 1933b: 247. house-mouse of Tibet”, Bonhot was seemingly Name combination. 142 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. impressed by the presence of a “surprisingly tame” 1986, Honacki et al. 1982, Musser & Carleton 1993, mouse inside the shrine, which was possibly an 2005, Zhang et al. 1997, Huang et al. 2008, Hu et al. additional inspiration for the new name. Perhaps even 2014, Jiang et al. 2015, Haslauer 2017c, f, Burgin et al. more relevant is the fact that in Bonhote’s time, lama 2020). Ross (1992) was uncertain over taxonomic status was used as species epithet for several taxa from Tibet, of the Ladakh hamster and although provisionally e.g. Lanius lama Dresser, 1905 (now Lanius tephronotus), synonymized lama, alticola and tibetanus with kamensis (p. and Microtus (Alticola) lama Barrett-Hamilton, 1900 (now 191), also concluded that “alticola […] is a species Alticola stoliczkanus lama); Ovis dalai-lama Przewalski, distinct from U. kamensis” (p. 198). In a revision of 1888 (now Ovis ammon dalailamae) is particularly Chinese mammals, Smith & Hoffmann (2008) elevated eloquent in this context. Similar inspirations in naming lama to a species rank, but did not comment on alticola, exotic taxa were not exceptional at the turn of the 19th which was in any case a geographical outlier. into 20th century, e. g. Evotomys mikado Thomas, 1905, Romanenko et al. (2021) finally classified lama, alticola, from Japan (now Clethrionomys rutilus), Tigris mikado and tibetanus as subspecies of alticola; here we treat them Satunin, 1915, from Korea (now Panthera tigris altaica), in similar way, although under lama, which is the oldest Micromys geisha Thomas, 1905, from Japan (now name in the group (cf. Peng et al. 2024). The scope of Apodemus argenteus), and Arvicola mandarinus A. Milne lama was defined by Ding & Liao (2019) who, however, Edwards, 1871, from China (now Lasiopodomys still classified it as a subspecies of kamensis. Prior to the mandarinus). Species epithets were derived from revision by Wang & Cheng (1973), Argyropulo (1933b, ‘Mikado’ (a Japanese word meaning ‘emperor’), ‘geisha’ c) recognized lama as a species in its own right with the (a female Japanese performing artist and entertainer), inclusion of alticola and tibetanus. Ellerman (1961) and and 'mandarin' (a high official in the Chinese empire). Ellerman & Morrison-Scott (1951) treated lama and alticola as independent species inside the lama group of Taxonomy. Wang & Cheng (1973) classified all forms Cricetulus. of Ladak Tibetan hamsters as subspecies (or synonyms) of Distribution. Range (area = 51,625 km2) covers the kamensis . Corbet (1978) accepted this view, though he simultaneously admitted southern and south-western border of the Tibetan alticola as a species in its own right. It therefore happened that taxa which are Plateau in southern Xizang (China), northern Nepal now inside (Pashchimanchal and Sudur Pashchimanchal), northern lama were split between 2 species, kamensis (with Uttaranchal and western Jammu and Kashmir in India, lama and tibetanus ) and alticola (Corbet & Hill 1980, Figure107: Distributional range of Ladak Tibetan hamster Urocricetus lama. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 143. and the Kongkashan Pass in extreme southern Xinjiang Ellerman 1941), but subsequent students synonymized (China) (Figure 107). This hamster occupies wide range tibetanus with lama (Ellerman & Morrison-Scott 1951, of habitats: mountainous coniferous and catawba Zheng 1986, Zhang et al. 1997, Luo et al. 2000, Wang forests, thickets, swampy meadows, alpine grassland, 2003). Romanenko et al. (2021) reinstalled tibetanus, farmland and human dwellings (Zheng 1986). largely following the results by Ding & Liao (2019) who Elevational range is 2,175–5,200 m (mean = 4,065 m), retrieved 3 genetic lineages of U. lama; 2 of these and Hu et al. (2014) stressed that U. lama ascends higher lineages are allopatric, while the third one overlaps with in the Mt. Qomolangma National Nature Reserve than both of them. Because of this overlap, we accepted 2 any other muroid rodent. subspecies admitted also by earlier authors. Characteristics. Dimensions: body mass = 22–48 g, Urocricetus lama lama (Bonhote, 1905) length of head and body = 84–103 mm, length of tail = 27–44 mm, length of hind foot = 15–18 mm, length of ear = 14–17 mm, condylobasal length of skull = 22.6– Synonym. Cricetulus alticola tibetanus Thomas & Hinton, 25.6 mm, zygomatic width = 12.5–14.7 mm, length of 1922. maxillary tooth-row = 3.7–4.2 mm. Relative length of tail varies depending on the subspecies, and accounts Distribution. The eastern portion of the species’ range, for 31–50% of the length of head and body. Dorsal to the east of ~ 86th meridian (Zheng 1986, Ding & Liao pelage is on average lighter than in 2019). kamensis , pale fulvous grey, beige-brown or greyish-brown (Figures 102 and 108); the chin and upper part of throat are Characteristics. Dimensions: body mass = 24–42 g, narrow median dusky streak along its upper surface; it 34–44 mm, length of hind foot = 15–18 mm, length of ear = 15–17 mm, condylobasal length of skull = 22.6– is never blackish dorsally as in white to hair bases. The tail is wholly white or with a length of head and body = 84–103 mm, length of tail = dentition as for the genus (Figures 103 and 104). 25.6 mm, zygomatic width = 12.7–14.7 mm, length of kamensis. Skull and maxillary tooth-row = 3.9–4.2 mm. Tail longer, accounting for 42–50% of length of head and body. Dorsal pelage darker, greyish-brown, tail with a narrow median dusky streak along its upper surface instead being wholly white (Figure 108a, b). Urocricetus lama alticola Thomas, 1917 Etymology. The epithet alticola is composed of Latin ‘altus’ for ‘high’ and ‘-cola’ for ‘dweller’ (from ‘colere’ meaning ‘to dwell’), i. e. a dweller of high elevations in allusion to its habitat. Distribution. The western portion of the species’ range, to the west of ~ 86th meridian (Zheng 1986, Ding & Liao 2019). Figure 108: Characteristics. Dimensions: body mass = 22–48 g, Skins of Ladak Tibetan hamsters Urocricetus lama in length of head and body = 85–103 mm, length of tail = lateral view: a, b – U. l. lama from Lhasa, Xizang, China (a), and Loro 27–37 mm, length of hind foot = 16–18 mm, length of Chu, Xizang, China (b); c – U. l. alticola from Ladak, Jammu and Kashmir, India. ear = 14–16 mm, condylobasal length of skull = 22.6– 24.6 mm, zygomatic width = 12.5–14.2 mm, length of Variation and subspecies. Early authors recognized 3 maxillary tooth-row = 3.7–4.2 mm. Tail shorter, subspecies (lama, alticola, tibetanus) (Argyropulo 1933b, c, accounting for 31–40% of length of head and body. 144 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Dorsal pelage on average lighter than in lama, pale (Figure 17c, d, f–h); if distal trident remains fulvous grey; tail entirely white or with slight brown cartilaginous, it is then distinctly longer than ½ of shade dorsally (Figures 102 & 108c). length of proximal stalk (Mesocricetus; Figure 17i); (6) the corneous epithelium of the stomach occupies most of SUBTRIBE: Phodopina – the glandular region (Figure 15b), but extends only New Subtribe along the border of isthmus in Urocricetina; (7) the stapedial artery is lost, which is reflected in the loss of Type genus. Phodopus Miller, 1910 groove (these structures are present in all the remaining spheno-frontal foramen and squamoso-alisphenoid Cricetinae) (Ross 1992). Diagnosis and Comparisons. Phodopina new subtribe differs from Urocricetina in nucleotide Phodopina contains 2 genera ( Content. Phodopus and sequences (Lebedev et al. 2018a, Romanenko et al. Cricetiscus ) with 3 recent species. The genera separated 2021) and in a set of morphological and chromosomal before the end of Miocene at an estimated 4.9–6.9 Mya particularities. In Phodopina, (1) the plantar surface is (Neumann et al. 2006) or 5.69 Mya (95% CI = 4.38– completely furry (Figure 109), while there is bare skin 7.04 Mya; Lebedev et al. 2018a), depending on the present between the pads in Urocricetina (Figure 101); marker and calibration point used. Alhajeri (2021) (2) the number of plantar pads is reduced to 3 or less, suggested a much older divergence of 10.9 Mya. while there are 6 plantar pads in Urocricetina; (3) the tail is vestigial (< 20% of head and body length), but The northern portion of the range of Distribution. normally developed in Urocricetina (longer than 20% Urocricetini in southern Siberia (the upper reaches of of head and body length); (4) the phallanges are the Ural, Tobol, Black Irtysh, Ob, and Yenisey), relatively shorter than in Urocricetina and the remaining northern and eastern Kazakhstan, Mongolia and hamsters, hence the species of Phodopina run at slow northern China, to the north of the Huang He and the speed and frequently move by hopping (Wynne- plateaus of Ordos and Tibet. Along the Tibetan Plateau, Edwards et al. 1992); (5) distal trident remains the range of Phodopina marginally overlaps that of cartilaginous and is less than ½ of the length of Urocricetina (Figure 100). proximal stalk 1 (Figure 17a, b); in the remaining hamsters, the distal trident is usually ossified and long Figure 109: Left palm in Phodopus roborovskii (a) and Cricetiscus sungorus (b, c, c’). Hairs are removed in insets a–c to expose pads (shaded dark grey). Digits are indicated by Roman numerals (I = thumb); scale bar = 5 mm. 1 In Nothocricetulus, the distal baculum is shorter than ½ of the proximal baculum, but is osseous (Figure 17e). SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 145. GENUS: Phodopus Miller, 1910 – Phodopus roborovskii (Satunin, 1902) – Desert Hamsters Desert Hamster Phodopus Miller, 1910: 498. Type species: Cricetulus Cricetulus roborovskii Satunin, 1902: 571. Syntypes are bedfordiae Thomas (= Phodopus roborovskii from “Oberlauf des Scharogol-dschin (Nan- Satunin). schan)” and “Syrtyn”. Type locality subsequently restricted to “the upper course of the Shara Gol Etymology. The generic name is a composite of in extreme western Nan Shan, China” (Allen ‘phodos’ (the genitive case of the Greek ‘phos’ for a 1940: 776). A lectotype (ZIN 5829) was collected ‘burn’ or ‘blister’) and ‘pous’ meaning ‘foot’ in Greek, from “верховиья р. Шароголджин в Нань-hence a ‘foot with a blister’ in allusion to the only Шане [upper reaches of the River Sharogoldzhin plantar pad present, which resumes shape of a large in Nan'-Shan']” (Gromov & Baranova 1981: blister or bubble (Figure 109a) (Ross 1994). 159), i. e. “верх. р. Шарогол-Джин (р. Шара- Гол), Нань-Шань, (Китай)” [upper reaches of Taxonomy. Phodopus traditionally encompasses all 3 the River Sharogol-Dzhin (River Shara-Gol), species of Phodopina. Cricetiscus, although described as Nan'-Shan' (China)] in Baranova & Gromov a genus in its own right (Thomas 1917), was only (2003: 45). Currently, the type locality is spelled exceptionally used that way (Howell 1929, Allen 1940), ‘the upper [part of] Scharogol-Dzhin [River but was mainly synonymized with Phodopus. Within valley], Qinghai, China’. Phodopus, some authors recognized 2 species groups (the [Cricetus (Cricetulus)] roborovskii: Trouessart, 1904: 395. sungorus group and the roborovskii group), which match Name combination. the current genera Cricetiscus and Phodopus, respectively Cricetulus bedfordiae Thomas, 1908a: 45. Type locality: (Ellerman 1941, Pavlinov & Rossolimo 1987, Pavlinov “Yu-lin-fu, Shen-si”, “4000’ [1,220 m] [added in et al. 1995); Lebedev (2012) ranked Cricetiscus as a Thomas 1908d: 975]”, amended to “Yulinfu, subgenus of Phodopus. Phylogenetic reconstructions North Shensi, China” (Ellerman & Morrison- based on molecular markers retrieved deep divergence Scott 1951: 628), currently Yulin, Shaanxi, China. between roborovskii on the one hand and sungorus + Phodopus bedfordiae: G. Allen, 1925: 7. Name campbelli on another hand. Based on this evidence, combination. Neumann et al. (2006) proposed a restoration of Phodopus praedilectus Mori, 1930: 418. Type locality: Cricetiscus as an independent genus, but their suggestion “Cheng-chia-tun, Central Manchuria”, China. gained no support (Feoktisova 2008, Smith & Phodopus roborovskii: Formozov, 1929: 54. First use of the Hoffmann 2008, Pardiñas et al. 2017, Burgin et al. current species name combination. 2020). We agree with Neumann et al. (2006) and classify Phodopus roborowskii: Argyropulo, 1933b: 244. Incorrect Phodopus and Cricetiscus as distinct genera. These genera subsequent spelling of roborovskii Satunin. diverged at an estimated 4.9±0.3–6.9±1.3 Mya Cricetulus roborovski: Chaworth-Musters, 1934: 591. (Neumann et al. 2006) or, according to a more recent Incorrect subsequent spelling of roborovskii estimation (Lebedev et al. 2018a), 5.69 Mya (96% CI = Satunin. 4.38–7.04 Mya). In the course of independent Phodopus roborovskii bedfordiae: Ellerman, 1941: 437. evolution, they accumulated ample morphological Name combination. synapomorphies (see below), which further support the Phodopus roborovskii praedilectus: Ellerman & Morrison-proposed taxonomy. Besides, Phodopus clearly differs Scott, 1951: 628. Name combination. from Crictiscus in various behavioural and physiological Phodopus przhewalskii Vorontsov & Krjukova, 1969b: characteristics, e. g. slower rates of growth and 102. Type locality: “пески востока Зайсанской behavioural development (Ross & Cameron 1989), котловины между Юлькен-Караталом [now faster response to changes in photoperiod and lower Улькен-Каратал] и Акжоном на левом берегу seasonal variation in body mass and testes size (Müller Черного Иртыша [sands of eastern Zaysan et al. 2015). Depression between Ul'ken-Karatal and Akzhon 146 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. on the left bank of the Black Irtysh]”, East Vorontsov & Krjukova (1969b) described a new species Kazakhstan Region, Kazakhstan. of desert hamster Phodopus przhewalskii from the Zaysan [Phodopus] przewalskii: Gromov & Baranova, 1981: 159. Depression in eastern Kazakhstan. The diagnosis was Incorrect subsequent spelling of przhewalskii based exclusively on karyology, i. e. 2n = 34 in the new Vorontsov & Krjukova, 1969. species, while 2n = 28 was taken from Matthey (1960) Ph[odopus] roborovskii przhewalskii: Vorontsov, 1982: 356. as the correct count in roborovskii. The latter report is an Name combination and new rank. evident error, and most likely refers to Cricetiscus Cricetulus betfordiae: Feoktisova, 2008: 14. Incorrect campbelli. Corbet (1978) synonymized przhewalskii with subsequent spelling of bedfordiae Thomas. roborovskii; Sludskiy (1977b) maintained it as a species in its own right, while Vorontsov (1982) and Shenbrot Etymology. The species epithet is eponym for (2017a) rank it as a subspecies of roborovskii. Vsevolod Ivanovich Roborovsky (Всеволод Иванович Роборовский, 1856–1910), a Russian army Distribution. Geographic range is wide but highly officer and participant of Przewalski’s expeditions to fragmented (area = 433,274 km2) due to narrow habitat Central Asia. He served as a natural history collector preferences of the species. The range covers north- and scientific illustrator, and secured syntypes of P. western and southern Mongolia and northern China, roborovskii. Roborovsky has eponyms also in reaching the margins of Kazakhstan, Russia and India herpetology, ornithology and botany. (Figure 110). Mongolian range encompasses the Great Lake Depression, Valley of Lakes and the Gobi Desert Taxonomy. We regard Phodopus as a monospecific to the south of the 44th parallel; desert hamsters are genus which, however, has not always been the case. absent from the Altai Mountain range, the Eastern Shortly after Satunin’s description of roborovskii, Sayan and the Khangay Range (cf. Sokolov & Orlov Thomas (1908a, d) named a new species bedfordiae, 1980). The north-western extension of Mongolian presumably on the basis of smaller size. Subsequent range in the Uvs Province marginally captures Tuva authors used bedfordiae and neglected roborovskii (Allen (Tyva) Province in Russian Federation (Flint 1960). In 1925, 1940, Howell 1929, Mori 1930); these 2 names China, the bulk of range overlaps with the Gobi Desert were synonymized around 1930 (Formozov 1929, and the Ordos Plateau in the Provinces of central Nei Argyropulo 1933a, b, Chaworth-Musters 1934). Mongol, Gansu, north-eastern Qinghai, Ningxia, northern Shaanxi, and northern Hebei. Further east, a Figure 110: Distributional range of the desert hamster Phodopus roborovskii. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 147. large fragment of geographic range is isolated by the pretty close with the spring vegetation cover of <20% Great Khingan mountain ridge; the fragment (cf. Figures 7 & 12 in Judger et al. 2018). Elevational encompasses eastern Inner Mongolia, western Jilin and range is 115–4,637 m (mean = 1,382 m). western Liaoning (Zhang et al. 1997, Luo et al. 2000, Wang 2003). The following population fragments are Characteristics. The smallest living hamster with a scattered at the periphery of northern and western short and broad torso (Figures 111c & 112). range borders (south-west to north-east): (1) Dimensions: body mass = 10.5–19 g, length of head Changthang Plateau (part of Tibet Plateau) in eastern and body = 66–86 mm, length of tail = 7–11 mm, Ladakh, India (Ramachandran et al. 2020) and Rutog length of hind foot = 10.5–12.0 mm, length of ear = 9– County in Xizang, China (Liu et al. 2020); (2) Altun 14 mm, condylobasal length of skull = 19.2–21.7 mm, Shan Mts. in southern Xinjiang (Zhang et al. 1997); (3) zygomatic width = 11.3–12.8 mm, length of maxillary Zaysan Basin in eastern Kazakhstan and adjacent tooth-row = 3.1–3.5 mm. Ears are moderately long, Xinjiang (China) northward and mainly eastward of the eyes fairly large; whiskers white and black, very dense upper Black Irtysh (Sludskiy 1977b, Zhang et al. 1997); and long (up to 25–30 mm). Tail is vestigial and stumpy (4) Uvs-Nuur depression (north-western Mongolia) and (Figure 113a), equalling 8–15% (usually ≈ 10%) of Tuva (southern Siberia); (5) Mongolyn-Els in Bulgan length of head and body; it is densely furry and the Province, Mongolia (vouchers in ZMMU); and (6) Xin terminal pencil is long (≈ 5 mm). Feet are unusually Barag You Qi in north- eastern Inner Mongolia (Xu short and broad, densely hairy throughout; plantar and 2016). palmar tubercles are confluent into a single blister-like mass (Miller 1910; Figure 109a). Fur is soft and fine, Desert hamsters inhabit sandy and sandy-gravel plains hairs on the mid-back measure 6–10.5 mm; sparse all- and the periphery of sand dunes and semi-fixed sands, black hairs protrude by up to 4 mm and are denser on but avoid inner parts of large sand massifs. They prefer the posterior rump. General dorsal colour is drab-grey sparse vegetation cover and avoid steppes and saline and clouded by grey hair bases; flanks are pinkish buff. habitats (Flint 1960, Sludskiy 1977b). In Mongolia, their Young hamsters tend to be darker. Undersurface from northern and north-eastern range border coincides just below the eyes, the limbs and the tail are pure Figure110: Distributional range of the desert hamster Phodopus roborovskii. Figure 111: Museum skins in dorsal view of Cricetiscus sungorus in summer (a1) and white winter (a2) pelage; C. campbelli (b) and Phodopus roborovskii (c). Museum vouchers originate from Karasukskiy Rayon (a1), Novosibirsk Oblast (a2), south-eastern Altay Republic (b), and Mongolia (c). Photo by B. Kryštufek (a1, a2 & b) and David Kunc (c) 148 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. snowy-white and the white of the lower side extends to width accounts for ~ 37% of length of the proximal dorsal side of the tail base (Figure 113a). The basal baculum. Distal trident is short and cartilaginous; its ⅘ of dorsal hairs are slate, while ventral hairs are white to length approximates 23% of length of the proximal base. Line of demarcation is well defined and serpentine stalk; the central distal digit is longer than the lateral with a distinct upward salient between the cheeks and ones (Tokuda 1941, Vorontsov 1982). shoulder and another one though less prominent, on hips. There are 2 white patches on the head, one over The skull is small and delicate, with widely expanded the eye and another below the ear; the latter is more zygomatic arches (Figure 114); zygomatic width prominent in adults. Ears are greyish brown. Females accounts for 56.7–63.8% of condylobasal length (mean have 4 pairs of nipples. = 59.6%). The nasals are truncate at the top and comparatively short, not reaching behind the level of lacrimals. The anterior edge of the superior maxillary root of zygoma forms right angle at its junction with the rostrum; zygomatic arches run parallel to sagittal plane. Zygomatic plate lacks the masseteric expansion and is therefore narrow; despite this, the infraorbital foramen is of myomorphous type (Figure 20f); zygomatic keel and notch are both absent. Interorbital region is flat and broad, nearly as wide as rostrum. There is no trace of supraorbital ridges. Braincase is rounded and broad, as wide as long; parietals extend across much of cranial roof, but the interparietal is rather small. The profile is evenly bowed and the skull is comparatively deep. Incisive foramens are wide and quite short, only slightly exceeding the length of maxillary tooth-row; posteriorly, they do not reach the level of M1. Hard palate and pterygoid fossa are wide. Bullae are small and flattened, with characteristic tube-shaped anterior portion; basioccipital bone is wide. Mandible shows no peculiarities except for a short coronoid process. Upper Figure 112: Desert hamster Phodopus roborovskii. Photo by incisors are opisthodont. The occlusal surface of molar Konstantin A. Rogovin (a) and Georgy Shenbrot (b) 3 cusps is simplified and M is reduced. The major cusps directly oppose each other forming transverse lophs; there are no internal fields (Figure 115). Corneous epithelium occupies most of glandular region of the inner stomach in Phodopus (Figure 15b), but extends only along the border of isthmus in Cricetiscus. Besides, Phodopus roborovski is the only true hamster Figure 113: Museum skins of Phodopus roborovskii (a) and Cricetiscus without pyloric glands in the glandular portion of the campbelli (b) in semi-caudal view. Dorsal side of the tail base is white stomach (Vorontsov 1967, 1982, Ross 1992). like the underside in Phodopus (a), and brown like the rest of back in Cricetiscus (b). Photo by David Kunc Karyotype: 2n = 34, NF = 59; 12 autosomal pairs are The glans penis is club-shaped with expanded distal biarmed and 4 pairs are acrocentric. Sex chromosomes portion. There are no dorsal or ventral papillae, while are of medium size; the X chromosome is the lingual papilla shows forked tip. Baculum (Figure submetacentric and the Y chromosome is acrocentric 17b) has moderately expanded lancelike base and its (Spyropoulos et al. 1982, Schmid et al. 1986). SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 149. Figure 114: Skull and mandible in Phodopina hamsters. Top to bottom: Phodopus roborovskii (Dundovi Province, Mongolia), Cricetiscus campbelli (Dornod Province, Mongolia), and C. sungorus (Karasukskiy Rayon, Russian Federation). Variation and subspecies. Subspecific taxonomy was considered P. roborovskii a monotypic species (Bannikov never comprehensively revised and the number of 1954, Gromov et al. 1963, Zhang et al. 1997, Luo et al. recognized subspecies varied from 2 subspecies 2000, Wang 2003). This is not surprising, given the lack (roborovskii and bedfordiae) in Argyropulo (1933c), 3 of obvious variation in colour, size and cranial subspecies (roborovskii, bedfordiae, praedilectus) in Ellerman proportions (e.g. Chugunov 1962). Phylogeographic & Morrison-Scott (1951) and 4 subspecies ( roborovskii, analysis of cytb fragment, however, retrieved significant bedfordiae, praedilectus, przhewalskii) in Vorontsov & structuring on the one hand and considerable Krjukova (1969b). Many authors, on the other hand, admixture of up to 4 different lineages in the central 150 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. part of the range on the other hand (Meschersky & Etymology. Cricetus with diminutive suffix (-iscus) Feoktisova 2011, Lv et al 2016). Based on these results, denotes a small (tiny) hamster, which is in allusion to a Shenbrot (2017a) tentatively admitted 3 subspecies small size of hairy-footed hamsters. (roborovskii, praedilectus, przhewalskii). As shown by an ongoing study (Feoktisova et al., in progress), the Taxonomy. Cricetiscus was described as a genus in its situation is even more complex with some 5 lineages as own right (Thomas 1917), but was only rarely ranked putative subspecies: (1) roborovskii lineage with this way (Howell 1929, Allen 1940); the name was distributional range in Qinghai, Tibet and north- usually synonymized with Phodopus (Formozov 1929, western India; (2) bedfordiae lineage which is admixture Tokuda 1941, and subsequent authors); see taxonomic of several genetic lineages from the central part of account on Phodopina. geographic range; (3) praedilectus lineage from China (north-western Jilin, northern Liaoning and eastern The prevailing view over the 20th century recognized a Inner Mongolia); (4) przhewalskii lineage in Kazakhstan single hairy-footed hamster (i. e. sungorus) and campbelli (eastern Zaysan Depression in the East-Kazakhstan was classified as its subspecies (Kuznetsov 1932, 1965, Region) and north-western Xinjiang in China; (5) Tyva Argyropulo 1933a, b, Chaworth-Musters 1934, Allen lineage from southern Tyva in Russian Federation. Any 1940, Ellerman 1941, Tokuda 1941, Kuznetzov 1944, of these subspecies (or lineages) has so far been defined Ellerman & Morrison-Scott 1951, Bannikov 1954, morphologically. We therefore leave subspecific Chugunov 1962, Kuzyakin 1963, Veselovsky et al. 1965, taxonomic of P. roborovskii unresolved, calling for a Shubin & Alimbaev 1977, Corbet 1978, Corbet & Hill thorough revision. 1980, 1986, Sokolov & Orlov 1980, Gromov & Baranova 1981, Honacki et al. 1982, Gromov & Erbajeva 1995, Zhang et al. 1997, Luo et al. 2000, Wang 2003); this view was strengthened by chromosomal similarities between sungorus and campbelli (Gamperl et al. 1977). During the late 1970s, the crossbreeding trials initiated by Yudin et al. (1979) demonstrated male sterility in interspecific hybrids. Sterility of F1 and backcross males was largely the consequence of various anomalies due to meiosis disorder, e. g. abnormal synaptonemal complexes, instable bivalents, abnormal pairing of sex chromosomes, and multiple abnormalities during spermatogenesis (Safronova et al. 1992, Sokolov & Vasil’eva 1994, Cherepanova et al. 1998, Levenkova 2003, Ishishita et al. 2015). These aberrations arrested spermatogenesis at the stage of Figure 115: Grinding pattern of upper (a, b) and lower (a’, b’) molars spermatocytes (Bikchurina 2023). Hybrids also showed in desert hamster Phodopus roborovskii. Lingual is to the left; scale bar = 1 mm. Voucher (a) originates from 59 km east of Manlai sum, aberrations in the morphology of seminiferous tubules Mongolia, and voucher (b) is from captive stock. and underdeveloped caudal parts of epididymis (Bikchurina et al. 2018). Although hybrid females are GENUS: Cricetiscus Thomas, 1917 – fertile (Feoktisova et al. 2019), they suffer high Hairy-footed Hamsters mortality rate during pregnancy; besides, their fertility is lower, and the F1 offspring shows developmental anomalies (Cherepanova et al. 1998). Cricetiscus Thomas, 1917: 456. Type species is Cricetulus campbelli Thomas. Cricetsicus: These results necessitated a 2-species solution for Prodopus Cricetiscus Carleton 1993, Pavlinov et al. 1995), which received : Vorontsov, 1958: 334. Incorrect subsequent further support from molecular analyses (Meshchersky spelling of Cricetiscus (Pavlinov & Rossolimo 1987, Musser & Thomas. Formozov, 1929: 52. Incorrect subsequent spelling of Phodopus in combination with sungorus. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 151. & Feoktistova 2009, Lebedev et al. 2018a). The 2 the cheeks, neck, behind the rib-cage and on a hip species of hairy-footed hamsters diverged at an (Figure 116). The light lateral patches are separated by estimated 0.8±0.1–1.0±0.1 Mya (Neumann et al. 2006). narrow strip-like ventral expansions of dark dorsal colouration; the most prominent expansions are behind Morphologically, sungorus and campbelli differ in fur the shoulders and in front of hips. Tail is densely colouration (Figures 111 & 116), thought the overlap covered by white hairs that form short terminal pencil; prevents safe classification of all individuals to one or dorsal side is frequently shaded buff. Hairs above the the other species; for sungorus cf. Figures 116a & 119b; tail base are of same colour as the rest of the back for campbelli cf. Figures 116b & 121a. Putative (Figure 113b). Black mid-dorsal line extends from head differences in skull proportions between sungorus and to rump. campbelli (cf. Ross (1992) were not confirmed in recent geometric morphometric study based on 2-dimensional cranial landmarks (Alhajeri 2021). Interspecific differences, however, were reported in physiology, activity patterns, and behaviour. In contrast to C. sungorus, C. campbelli starts nocturnal activity earlier and remains active for longer (Wynne-Edwards et al. 1999). It is not so well adapted to cold temperatures (Weiner & Heldmeir 1987) and shows biparental behaviour, while sungorus is alloparental (Wynne-Edwards 1995). Additionally, maternal reserves are used differently during reproduction (Wynne-Edwards & Lisk 1987). Distribution. Steppes of southern Siberia and northern Kazakhstan (eastward of the upper reaches of the Ural and Tobol rivers) and south-eastern Russia as far east as the upper reaches of the River Amur; Mongolia and Figure 116: Museum skins of Cricetiscus sungorus (a) and C. campbelli Nei Mongol (China) south to the Huang He River and (b) in semilateral view. C. sungorus is characterized by bolder the Ordos Loop. Cricetiscus sungorus and C. campbelli have blackish-brown shoulder stripe and wider mid-dorsal stripe on the Pleistocene, of the white underside on the cheeks, neck, behind the rib-cage and Cricetiscus expanded its range westward and on hip. Vouchers: a – Krasnoyarsk Region, b – Tuva (Tyva) (both reached Europe (Maul 1990). allopatric ranges with no overlap. In the Early crown. Note sinuous lateral line and associated upward extensions in Russian Federation). Characteristics. Small hamsters with vestigial tail The skull is small and delicate (Figure 114); zygomatic (Figure 111a, b) and short but broad feet; soles and arches are less expanded than in Phodopus and zygomatic palms are densely haired; the only 3 small interdigital width accounts for 53.8–61.7% of condylobasal length plantar pads are entirely concealed by hair (Figure 109b, (mean = 57.5%). The nasals are long and reach behind c, c’). Ears are fairly short and the eyes are quite large. the level of lacrimals. The anterior edge of the superior Tail is hardly projecting from the fur (Figures 113 & maxillary root of zygoma forms a smooth curve at its 121b) and accounts for 9–15% (mean ≈ 13%) of length junction with the rostrum. Zygomatic plate is wider of head and body. Pelage is dense and soft. Back is light- than in Phodopus; infraorbital foramen is of to-dark grey with various admixtures of buffy tints. myomorphous type, being expanded dorsally and Underside is frequently shaded by grey hair bases and narrowed in its ventral half (Figure 20c). Zygomatic keel although hairs may be white throughout, the underside and notch are largelly absent. Interorbital region is is not as purely white as in Phodopus; the exception is narrower than in Phodopus; supraorbital ridges are white winter pelage of P. sungorus (Figure 111a2 & 119a). absent. Braincase is broad but more of diamond shape The lateral line is undulating and white fur of the lower than circular. Parietals are les expanded than in side extends up on the flanks forming convex areas on Phodopus. The profile is bowed but the skull is shallower 152 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 117: Grinding pattern of upper (a–c) and lower (a’–c’) molars in hairy-footed hamsters: a, b – Cricetiscus sungorus from Minusinskiy Rayon (a) and Barabinskiy Rayon (b; Russian Federation); c – C. campbelli from Chono Karaikhyn gol, Mongolia. Lingual is to the left; scale bar = 1 mm. than in Phodopus. Incisive foramens are narrower but Key to species longer than in Phodopus, and clearly exceed the length of maxillary tooth-row; posteriorly, they hardly reach the 1a) Dorsal fur is duller (Figures 111a1, 116a); mid- level of M1. The hard palate, pterygoid fossa and dorsal stripe is bolder and longer (anteriorly basioccipital bone are narrower than in Phodopus. Bullae reaching the level of eyes), with fuzzy edges; the are flattened, with a characteristic tube-shaped anterior stripe is widened on the front; a transverse stripe portion; they are comparatively larger than in Phodopus. behind shoulders is frequently present; a bold Mandible is the same as in Phodopus, though the blackish blotch is present on shoulders1; winter fur coronoid process tends to be longer. Upper incisors are is white (Figures 111a2, 119a); allopatric with orthodont. The occlusal surface of molar cusps respect to campbelli, present in Kazakhstan and resembles condition in Urocricetus; the major cusps southern Asiatic Russia (administrative regions of alternate and there are closed internal fields on the Orenburg, Chelyabinsk, Kurgan, Tyumen, Omsk, upper molars. The M3 is of normal size, accounting for Novosibirsk, Altayskiy Kray, Krasnoyarsk and c. ¼ of the upper tooth-row (Figure 117). Khakasia; Figure 118) ……………….…. sungorus 1b) Dorsal fur paler (Figures 111b, 116b); mid-dorsal Karyotype: 2n = 28, NF = 51 (males) or 52 (females), stripe narrower and shorter (anteriorly not NFa = 48; 11 autosomal pairs are biarmed and 2 pairs reaching the level of eyes), with sharp edges; the are acrocentric; the X chromosome is large metacentric stripe is usually not widened on the front; and the Y chromosome is small acrocentric. transverse stripe behind shoulders usually absent; Conventionally stained karyotypes of C. campbelli and C. blotch on shoulders weakly expressed or absent1; sungorus are identical (Gamperl et al. 1977, Schmidt et al. winter and summer fur are of similar colour; 1986, Romanenko et al. 2007); interspecific differences allopatric with respect to sungorus, present in become apparent in C-banded chromosomes Mongolia, China, and southern Asiatic Russia (Safronova et al. 1992). (administrative regions Altai Republic, Tuva, Buryatya and Chita; Figure 120) ……………………………………...…. campbelli 1 1 Colour traits vary and the typical condition for one species may be seen as an extreme in the opposite species; for extreme colouration of sungorus cf. Figure 119b; for campbelli cf. Figure 121a. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 153. Cricetiscus sungorus Pallas, 1773 – Taxonomy. In the past, C. sungorus frequently Siberian Hairy-footed Hamster comprised campbelli as a junior synonym or a subspecies (see taxonomic account on Cricetiscus). Trouessart Mus sungorus Pallas, 1773: 703. Type locality: “in campis ) with (1904: 395) synonymized kozlovi Satunin (now in Nothocricetulus C. sungorus. elatis, aridis, auſtralioribus Irtin [in the elevated dry Mus songarus plains of River Irtysh]”. Pallas obtained first The range extends over southern Siberia Distribution. specimens at “Gratschefskoi [Gratſcheſfkoi; Pallas encompassing northern Kazakhstan and adjacent 1773: 493] (Gratschewsk) on the Irtish [Irtysh] River Russia between the upper reaches of the rivers Ural in about 100 kilometres west of Semipalatinsk, S.W. the west and Yenisei in the east (Figure 118). The range [south-western] Siberia” Chaworth-Musters (1934: covers surface area of an estimated 677,955 km 2 . 590); in current spelling: Grachevskiy [ Грачевский], Distribution is largely contiguous between the Ural and 100 km west of Semipalatinsk (Semey [ Семей]), Ob rivers in Kazakhstan (provinces of northern Abai Region, eastern Kazakhstan (cf. Pavlinov & Qostanay, the entire North Kazakhstan, eastern Rossolimo 1987: 171). Aqmola, northern Qaraghandy, Pavlodar, eastern East Pallas, 1779: 269. Type locality: “ad Irtin in Kazakhstan; Afanasiev 1960, Shubin & Alimbaev 1977) auſtralibus Barabenſium camporum [Irtysh, and southern Russia (provinces of Orenburg, especially southward to the Baraba plains]”. It is Cheljabinsk, Kurgan, Tyumen, Omsk, Novosibirsk, unclear why Pallas was not consistent in spelling the Altayskiy Kray; Malykova et al. 2005, Snit’ko 2017, name. As shown by Thomas (1917: 452) and Ryabitseva 2020, Modorov & Polyakov 2021). The Chaworth-Musters (1934: 590), the 1773 name was range is increasingly fragmented further south in not a misprint, hence songarus is not an emendation Central Kazakhstan (southern Qostanay, southern of sungorus (as suggested in Pavlinov & Rossolimo Aqmola, central Qaraghandy, and southern East 1987: 171); besides, sungorus is used also in Kazakhstan). There is an eastern isolate in Minussinsk entomology (as sungora ; Chaworth-Musters l. c. ). Depression (in the Krasnoyarsk and Khakasia M[us] Cricetus songarus: J. F. Gmelin, 1792: 244. Name provinces); hamsters were recorded on both banks of combination. the Yenisei River (Yudin et al. 1979). The Siberian Cric[etus] songarus : Brandt, 1859: 211. Name hairy-footed hamster is also known from a single combination. locality in Kemerovo. The species putatively expanded Phodopus sungorus: Hollister, 1912: 3. Name combination. its range prior to 1940 (Afanasiev 1953). Cricetiscus sungorus: Thomas, 1917: 457. First use of the Cricetulus zongarus: current species name combination. Inhabitant of zones of forest steppe, steppe and Pidoplitshka, 1928: 416. Incorrect semidesert. Preferred habitat is ungrazed, short-grass subsequent spelling of sungorus Pallas, and name steppe on black and brown soils; present also on fixed combination. sands and saline substrate. Also occupies arable land Phodopus songarus: Argyropulo, 1931: 60. Name under grain crops and perennial grasses and combination. occasionally also forest clearings (Beljaev 1933, Phodopus subgorus: Sokolov & Orlov, 1980: 118. Afanasiev 1953, 1960, Flint 1966b). Not recorded in Incorrect subsequent spelling of sungorus Pallas. buildings (Ryabitseva 2020). Cricetiscus sungorus is a Etymology. The species epithet is derived from = 257 m). Higher elevations reported in older literature, flatland dweller, found at elevations of 64–898 m (mean ‘Dzungaria’ (also Sungaria or Junggar), which comes up to 3,000 m in Chuyskaya Steppe, Atlai Republic, e.g. from Mongolian ‘Zűn Gar’ or ‘Jüün Gar’, meaning ‘left Russia (Yudin et al. 1979), relate to campbelli . hand’. Cricetiscus sungorus is absent from Dzungaria as is currently defined (in northern Xinjiang, China), are the same as for the genus. Characteristics however, its range partly overlapped the historical Dimensions: body mass = 19–45 g, length of head and Dzungar Khaganate of the Oirat Mongols, which body = 78–102 mm, length of tail = 5–15 mm, length included the upper Irtysh River in the present-day of hind foot = 12–15 mm, length of ear = 11–16 mm, Russian Federation. 154 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. Figure 118: Distributional range of the Siberian hairy-footed hamster Cricetiscus sungorus. condylobasal length of skull = 20.5–25.4 mm, shoulders in particular may remain grey (Figure 119a). zygomatic width = 12.0–16.1 mm, length of maxillary Ventral hairs of winter fur are white to bases. Moult into tooth-row = 3.3–4.1 mm (Shubin & Alimbaev 1977); summer fur occurs in February–March (Shubin & there is no secondary sex dimorphism. Pelage shows Alimbaev 1977) in a reverse section (Figala et al. 1973). seasonal polyphenism with white winter colouration In addition to pigmentation, the winter moult affects (Figures 111 & 119). Dorsally, the summer fur is dull the overall length of the hairs (the winter hairs are ash grey to dark brown (Figures 111a1, 116a); rarely, the longer), but not the hair density (Kuhlmann et al. 2003). back is pale brownish-grey (Figure 119b). The blackish- brown mid-dorsal stripe is normally bold but with fuzzy Glans penis is egg-shaped with a truncate tip. There are edges, and extends from the eye level on the front back no dorsal or ventral papillae; lingual papilla has forked to tail base. The stripe is usually widened on the front tip. Baculum has moderately expanded lancelike base; and shoulders (Figures 111a1, 116a). A blackish lateral the width of base accounts for ~ 44% of length of streak is typically bold and may extend from post- proximal stalk. Distal trident is moderately long and auricular region back to the tights (Figure 116a); its cartilaginous; its length approximates ~ 35% of length lower edge is irregular. Besides, many individuals show of proximal baculum (Figure 17a) (Vorontsov 1982). an additional transverse stripe across the shoulders The skull and dentition are the same as in the genus (see which, however, is less prominent (Figures 111a1). In above; Figures 114 and 117a, b). Karyotype is as for the extreme cases, these black markings may be much less genus (Vorontzov 1958, Soldatović et al. 1971, bold and resemble the situation in C. campbelli (Figure Gamperl et al. 1977, Romanenko et al. 2007). 119b). White or yellowish postauricular patches are usually present (typically absent in C. campbelli). Hairs Variation and subspecies. Kuznetsov (1932) are white to the base on parts of or the entire underside. distinguished 2 geographical races in Kazakhstan. He Ears are grey to blackish; the paws are greyish-white and characterized the nominotypical race by light greyish- the tail is whitish with yellowish shade. Moult into white drab back, white belly, longer spinal stripe (extending winter fur proceeds in November–December from the from occipital region to sacrum), and pure white paws. rump and progresses onto the back, the postauricular This race occupies steppes of western Siberia and region, the face and the flanks (the winter moult). The north-eastern Kazakhstan. An unnamed race from mid-dorsal and the transverse stripes persist throughout Central Siberia (regions of Minusinsk, Irkutsk, and winter, albeit in a reduced extent (Figure 111a2); Yeniseysk) was characterized by domination of brown SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 155. tints, specifically by grey-brown back darkened by black (also Shabarte’), which is a common name for hair tips, a shorter spinal stripe (starting on the front), temporary lakes, is frequently incorrectly reported ventral hairs with grey bases, and brown hairs on the for eastern Mongolia instead for Nei Mongol in proximal part of hind paws. Because no subspecies China: “approximately 500 km east of Urga (Ulan- were validly proposed, C. sungorus is technically still Bator-Hoto [Ulaanbaatar]), Mongolia” (Argyropulo regarded as monotypic species (Ross 1992, Shenbrot 1933c: 136, Bannikov 1954: 453), “42°40’ north 2017c). latitude, 110° east longitude” (Allen 1940: 773), and northern (Ellerman & Morrison-Scott 1951: 627) or north-eastern Mongolia (Ellerman 1941: 437, Musser & Carleton 2005: 1045). Phodopus crepidatus Hollister, 1912: 3. “Chuisaya [correct spelling is Chuyskaya] Steppe (eight miles [13 km] south of Kosh-Agatch), Altai District, Siberia; altitude 7300 feet [2,225 m]”, i. e. 13 km south of Kosh-Agach, Kosh-Agachkiy District, Altai Republic, Russian Federation. P[hodopus] campbelli: Hollister, 1912: 3. Name combination. Cricetiscus campbelli: Thomas, 1917: 456. First use of the current species name combination. Cricetiscus crepidatus: G. Allen, 1925: 7. Name combination. Phodopus (Cricetsicus) [sic] sungorus campbelli: Formozov, 1929: 52. Name combination. P[hodopus] campbell: Mori, 1930: 418. Incorrect subsequent spelling of campbelli Thomas. Phodopus sungorus crepidatus: Chaworth-Musters, 1934: 591. Name combination. Cricetiscus sungorus campbelli: Allen, 1940: 773. Name combination. Figure 119: Siberian hairy-footed hamster Cricetiscus sungorus in Phodopus cricedatus: Shubin & Alimbaev, 1977: 457. summer fur (b; Altaysky Kray, Russia) and in white winter pelage (a; Incorrect subsequent spelling of crepidatus Hollister. Khakasia, Russia). Note that specimen (a) still has ample dark summer hairs on head and back; individual (b) represents a light- Etymology. Species epithet is eponym to Charles coloured form with ill-defined dorsal stripe and blotches on shoulders. Photo M. Kabanov (a) and Georgy Shenbrot (b) William Campbell (1861–1927), the British Consul in China, who organized the 1902 travel to Mongolia (incl. Cricetiscus campbelli Inner Mongolia; cf. Campbell 1903), during which the (Thomas, 1905) – type and the paratype specimens of campbelli were Mongolian Hairy-footed Hamster collected. Cricetulus Campbelli Thomas, 1905: 322. Type locality Taxonomy. Musser & Carleton (1993: 539, 2005: “Shaborte, N.E Mongolia (about 42°40’ N., 114° 1045) listed in the synonymy of campbelli also “tuvinicus E.)” was subsequently amended to “42°40’ N., Orlov and Iskharova (sic), 1974”, referring to “Pavlinov can deduct from Campbell’s (1903) expeditionary paragraph dealing with tuvinicus in Pavlinov & report, the type locality is most probably identical to Rossolimo ( 116°20’ E.” (Thomas 1908e: 107 footnote). As one and Rossolimo 1987: 171”. Transliteration of the entire l. c.) reads as follows: “?1981. Phodopus the current Zhenglanqi, Xilin Gol, Inner Mongolia, sungorus tuvinicus ‘Orlov et Iskhakova, 1974’ China (coordinates 42.6981 north latitude, 116.3576 anonym[ous], in the book: Catalogue of mammals of east longitude) (Shenbrot 2017b: 281). ‘Shaborte‘ 156 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. USSR: 158. Tyva ASSR [Autonomous Soviet Socialist set by the upper reaches of the Irtysh, Ob, Yenisei, Republic] (by tautonomy). Nom[en] nudum (no Amur and Baikal Lake, and the southern border is on description, no authorship).” The book from 1981 is the great loop of the Huang He River. The species is obviously the Catalogue by Gromov & Baranova (1981) widespread in Mongolia; the only exception is northern who on p. 158 indeed listed among synonyms of C. Ksövgöl where C. campbelli does not occur; in addition, sungorus also “tuvinicus Orlov et Iskharova (sic), 1974 records are scarce to the south of the 45th parallel. In (Tuva, nomen nudum?).” To best of our knowledge, the north-west, the range expands from Bayan-Ölgii Orlov & Iskhakova published no joint paper in 1974, and Uvs (Mongolia) into southern Altai Republic and but have such a publication in 1975 dealing with the southern Tyva (Russian Federation). Further taxonomy of Cricetulus barabensis. Noteworthy, Gromov northward, expansions from Mongolia into Russia are & Baranova (1981: 157) listed another “tuvinicus Orlov into southern Buryatia and north-eastern Chita. In et Iskharova (sic), 1974”, this time as a synonym of China, the bulk of range is in eastern and central Nei Cricetulus barabensis. The entire issue with tuvinicus is Mongol with slight extensions into north-western therefore pretty messy and in our firm belief this name Hebei and Ningxia, with the most exposed southern was never validly proposed for Cricetiscus. The name record for the species. “Phodopus sungorus tuvinicus Orlov & Iskhakova, 1974” as it appeared in Gromov & Baranova (1981) and The Mongolian hairy-footed hamster inhabits high-Pavlinov and Rossolimo (1987) was never properly elevation steppe with Artemisia and Festuca, stabilized published and is therefore unavailable name. sand dunes dominated by Caragana shrubs, river valleys, sandy or saline banks of lakes, and cultivated land In the past, campbelli was nearly universally treated as a (Bannikov 1954, Chugunov 1962, Flint 1966b). junior synonym of C. sungorus or its subspecies (see Elevational range is 145–3,390 m (mean = 1,322 m). taxonomic account on Cricetiscus). Characteristics. Size and proportions are as in C. Distribution. The range extends across an estimated sungorus. Dimensions: body mass = 13–43 g, length of 969,658 km2 in eastern Nei Mongol and Mongolia, from head and body = 85–103 mm, length of tail = 5–16 mm, where it marginally also encompasses adjacent parts of length of hind foot = 10–15 mm, length of ear = 8–17 Russia (Figure 120). The northern border is tentatively mm, condylobasal length of skull = 20.8–25.5 mm, Figure 120: Distributional range of the Mongolian hairy-footed hamster Cricetiscus campbelli. SUBFAMILY: Cricetinae Fischer, 1817 – TRUE HAMSTERS 157. zygomatic width = 11.7–15.1 mm, length of maxillary ground (Allen 1925, Chaworth-Musters 1934, Ross tooth-row = 3.3–4.3 mm. Colouration is on average 1992) and Ross (l. c.) strongly argued that crepidatus is paler than in sungorus. Dorsal pelage is grey-buff tipped sufficiently distinct to merit subspecific status at least. with black; the face, the area around the ears, the shoulders, and the flanks may have more buffy tint; the lips and cheeks are cream-white. The blackish mid- dorsal stripe is on average narrower than in C. sungorus; variation is, however, considerable and the stripe varies from a faded line in light-coloured individuals (Figure 121b) to a bold one in those with brighter colouration (Figure 121a). As a rule, the stripe is not bold on the front and terminates before the tail base; it is the boldest between the shoulders and the rump. The lateral streak is typically absent (Figure 121b) and only rarely prominent (Figure 121a); the majority of hamsters show a yellow or buffy dividing line between the dorsal and the ventral pelage (Figure 116b). The transverse stripe across the shoulders is absent. Hairs on the underside have slate bases and white to creamy-buff tips; the paws and the tail are silvery-white or cream-buff, and the ears are grey. Winter pelage does not differ essentially from the summer one. The skull and dentition are as in the genus (see above; Figures 114 & 117c). The same also holds for the karyotype (Safronova et al. 1992, Romanenko et al. 2007, Ishishita et al. 2015). Variation and subspecies. Phylogeographic analysis based on partial mtDNA sequences retrieved three Figure 121: Mongolian hairy-footed hamster Cricetiscus campbelli lineages (the East, the West, and the Kosh-Agach from Mongolia. Note differences in fur colouration. Photo courtesy lineages). The major division is between the West and by Konstantin A. Rogovin (a) and Nedko Nedyalkov (b) the East lineages in the Khangai mountain range (at approximately 100–102nd eastern meridian) and dates Cricetiscus campbelli campbelli back to around 0.45–0.55 Mya. There is an outlier of (Thomas, 1905) the West lineage in Dauria (south-eastern Transbaikalia, Russia), deeply inside the range of the East lineage. The Kosh-Agach lineage is nested inside the West lineage Distribution. Central and eastern Mongolia and China and diverged approximately 0.34–0.42 Mya (Inner Mongolia, western Ningxia and northern Hebei) (Shenbrot 2017b). (Meshchersky & Feoktisova 2009). The major phylogenetic lineages are classified as distinct subspecies, the nominotypical subspecies (lineage East) Characteristics. Dorsal pelage is greyish-buff, the mid- and dorsal stripe runs from between the ears to the tail base; crepidatus (lineage West with the inclusion of lineage the tail, tips of the ears, and forearms are washed beige. Kosh-Agach) (Shenbrot 2017b). Due to the low The skull is on average shorter and wider; auditory sampling density, in addition to the presence of an bullae are more flattened and the eustachian tube is obvious outlier, the proposed classification has to be more elongated. The transverse ridge formed by the taken with caution. On the other hand, the two anterocone of M 1 is narrower than the width across the subspecies were recognized already on morphological paracone–protocone; in a worn stage, the anterior 158 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. medial fold separating the lingual and the buccal Mongolia (Shenbrot 2017b); there is an isolate of the anterocones persists for longer than in crepidatus (Ross West lineage in Dauria (south-eastern Transbaikalia, 1992). Russia), on the eastern edge of the presumed range of the nominotypical subspecies. Cricetiscus campbelli crepidatus (Hollister, 1912) Characteristics. Dorsal pelage is wood-brown, the mid-dorsal stripe runs from the shoulder to Etymology. The Latin word ‘crepidatus’ originates of the ears, and forearms are white with no beige tint. approximately 2–3 cm above the tail base; the tail, tips from ‘crepida’ (sandal) and means ‘wearing sandals’, in The skull is on average longer and narrower; auditory allusion to heavily hairy soles in Cricetiscus . bullae are more swollen and the eustachian tube is more Distribution. South-eastern Siberia in Russian (Altai anterocones lacks the anterior medial fold, separating rounded. In a worn stage of M1, the ridge formed by the Mts., Tyva, Buryatia, Chita) and north-western the lingual and the buccal cones (Ross 1992). TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot References Transliteration The papers quoted below have been published in various languages and scripts found across the Palaearctic Region. Many important works are in Slavic languages (in particular Russian), Chinese, Korean, and Japanese, to mention just the main linguistic groups. 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Tolbukhin 1: 151–165 [in Bulgarian with Russian and German summaries]. Zolotarev N.T. (1936). Mammals of the Iman River Basin (Ussuri Land). Acad. Sci. Press, Moscow [in Russian with Eng. title page]. Zoltán B. (2007). [Common hamster Cricetus cricetus (Linnaeus, 1758)]. In: Zoltán B., Csorba G. & Miklós H. (Eds.) [Atlas of Hungarian mammals.] Kossuth Kiadó, Budapest, pp. 176–178 [in Hungarian]. Zykov A.E. (1991). [Systematic-faunsitic and zoogeographical analysis of small mammals (Insectivora, Rodentia, Lagomorpha) of Kopet Dag]. Ph.D. Thesis, Kiev, AN USSR, Institut zoologii im. I. I. Shmal'gauzena, 295 pp. [in Russian]. TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION B. Kryštufek, G. I. Shenbrot Index to the technical names Each species group name is entered only once, under the genus in which it is recognized in this book. Names of extant Palaearctic arvicolines printed in bold face are those which are given full status. Family group names are in small capitals. Bold face figures refer to the pages of the detailed description. accedula, Nothocricetulus, 4, 65, 66, 69, 76, acredula, Nothocricetulus, 65, 69 AKODONTINI, 44 albipes, Tscherskia, 30, 31, 32, 38, 39 albus, Cricetus, 92 Allocricetulus, 4, 6, 7, 11–18, 21, 28, 29, 31, 41, 42, 49, 68, 77–81, 82, 83, 85–90, 94, 111, 112 Allocricetus, 68, 69, 78, 82 altaica, Panthera, 142 Alticola, 13, 137 alticola, Urocricetus, 135, 137, 139, 141, 142, 143–144 ammon, Ovis 142 andersoni, Cricetulus, 59–61, 63 Apodemus, 142 arenarius, Nothocricetulus, 4, 64–66, 69, 76 argentatus, Alticola, 137 argenteus, Apodemus, 142 armatus, Mesocricetus, 131 Arvicola, 65, 76, 142 ARVICOLINAE, iii, 3, 4, 11–15, 18 Asiocricetus, 30, 32, 38 ASPALACIDAE, 3 atticus, Nothocricetulus, 4, 66, 69, 76 auratus, Mesocricetus, 4, 9–18, 21, 22, 112, 114–116, 117–121, 122, 126, 127, 130–133 avaricus, Mesocricetus, 121, 122, 124 babylonicus, Cricetus, 93 babylonius, Cricetus, 93 bampensis, Tscherskia, 30, 32, 38 barabensis, Cricetulus, 3–5, 13–15, 18, 21, 42, 43, 44–56, 57–59, 61–63, 66, 68, 69, 111, 113, 156, bedfordiae, Phodopus, 145, 146, 149, 150 belajevi, Allocricetulus, 82–84 beljaevi, Allocricetulus, 82–87 beljawi, Allocricetulus, 82 bellicosus, Nothocricetulus, 66, 75, 76 Boreoeutheria, 26 brandti, Mesocricetus, 112, 113, 115, 117, 118, 122, 126, 127, 129, 130–134, BUCCATI, 3, 26 178 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. bursae, Allocricetus, 68, 69, 78, caesius, Nothocricetulus, 66, 68, 75, 76 CALOMYSCIDAE, 3–5 Calomyscus, 3, 5 campbelli, Cricetiscus, 14, 145–154, 155–158 canescens, Cricetus, 91–93, 104 CANSUMYINA, 6, 29, 105 Cansumys, 5–7, 11, 13, 15, 18, 20–22, 27, 29, 31, 40–42, 78, 105–109 canus, Cansumys, 9, 31, 32, 40, 105–109 Chinchilla, 3, 90 Chinchillula, 4 chiumalaiensis, Cricetulus, 61, 63, 64 cinerascens, Nothocricetulus, 65, 67, 69, 75, 76 cinereus, Nothocricetulus, 67, 75, 76 citellus, Spermophilus, 3 coerulescens, Nothocricetulus, 65–69, 75, 76 collina, Tscherskia, 31, 35, 37, 39–41 collinus, Tscherskia, 39, 40 crepidatus, Cricetiscus, 155, 157, 158 CRICETI, 4, 26, CRICETIDAE, 3–5, 18, 26 CRICETINA, 6, 7, 12, 13–16, 26, 28, 29, 30, 41, 49, 79, 90, 97, 105 CRICETINAE, 3–7, 12, 14–16, 21–23, 26, 29–31, 37, 90, 94, 97, 111, 113, 135, 141, 144 CRICETINI, 5, 6, 14, 26, 27, 29, 105, 111, 112, 135 CRICETINORUM, 3, 26 Cricetinus, 30 Cricetiscus, 27, 90, 135, 144–149, 150–152, 153–158 Cricetulus, 3–6, 11–18, 20, 21, 28–32, 35, 36, 38–39, 41–44, 45–73, 75–78, 82, 87, 88, 90, 105–107, 112, 113, 134, 137–139, 141–143, 145 Cricetus, 3–7, 26, 28–31, 41–44, 54, 59, 65, 66–68, 76, 77, 78, 82, 90–92, 111, 117, 121–123, 126, 130, 131, 137, 139, 145, 150, 153 cricetus, Cricetus, 3, 4, 7, 9–22, 49, 90, 91, 92–104, 109, 111–114 CUNICULARII, 3 curtatus, Allocricetulus, 14, 18, 21, 78–82, 85, 86, 87–90 dalailamae, Ovis, 142 dichrootis, Cricetulus, 4, 46, 59, 61, 63, 64 elisarjewi, Nothocricetulus, 67, 68, 76 Euarchantoglires, 26 Eutheria, 26 eversmanni, Allocricetulus, 4, 12–15, 18, 49, 77–81, 82–87, 88–90, 112 Evotomys,142 falzfeini, Nothocricetulus, 66, 67, 77 ferrugineus, Cricetulus, 45, 53–54 frumentarius, Cricetus, 92, 92, 131 Index to the technical names 179. fulvus, Cricetus, 92 fulvus, Nothocricetulus, 65, 66, 69, 76 fumatus, Cricetulus, 44, 45, 52, 53, 54 furunculus, Cricetulus, 4, 44–46, 52, 55 fuscatus, Cricetus, 4, 92 fuscidorcis, Cricetus, 93 fuscipes, Tscherskia, 32, 37–39 geisha, Apodemus, 142 GERBILLINAE, 3 germanicus, Cricetus, 92 Glires, 26 Glis, 44, 65, 92 griseiventris, Cricetulus, 66 griseiventris, Nothocricetulus, 59–63 griseus, Cricetulus, 4, 14, 41, 44–48, 51–53, 54–55, 56, 58, 112, 113 griseus, Nothocricetulus, 66, 67, 76 Hamster, 92 Heliomys, 90, 92–94 Hesperomys, 4, 44, 90 incana , Tscherskia, 32, 37, 38, incanus, Tscherskia, 31, 32 isabellinus, Nothocricetulus, 65, 68, 69, 76 jesreelicus, Allocricetus, 78 jeudei, Cricetus, 90, 92–94 kamensis, Urocricetus, 4, 11, 30, 61, 68, 69, 136, 138, 139–141, 141–143 koenigi, Mesocricetus, 4, 112, 130, 131, 134 Kowalskia, 30 kozhantscikovi, Cricetulus, 60, 62, 63 kozlovi, Nothocricetulus, 4, 46, 61, 66–69, 75, 76, 139, 153 lama, Alticola, 142 lama, Urocricetus, 62, 68, 73, 136–139, 141–144 Lanius, 142 Lasiopodomys, 142 latycranius, Cricetus, 93, 94 Lemmus, 13 lemmus, Lemmus, 13 longicaudatus, Cricetulus, 4, 5, 30, 42, 43, 45, 46, 49, 50, 57, 59–64, 66, 68, 71, 137, 139 Mammalia, 26 manchuricus, Cricetulus, 44, 45, 52, 53 mandarinus, Lasiopodomys, 142 Marmota, 90 180 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. marmota, Marmota, 3 meihsienensis, Tscherskia, 39, 40 MESOCRICETINI, 6, 14, 16, 29, 111–112, 135, Mesocricetus, 4–7, 9, 10, 12–18, 20–22, 27, 30, 77, 78, 82, 86, 90, 111, 112–117, 118–134 microdon, Allocricetulus, 82, 85–87 Micromys, 142 Microtus, 65, 142 migratorius, Nothocricetulus, 3, 4, 7, 11, 13–15, 18, 21, 22, 41, 42, 46, 49, 62, 63, 64–77, 82, 87, 88, 135, 137, 139 mikado, Clethrionomys, 142 mikado, Panthera, 142 mongolicus, Cricetulus, 44, 54 MURES, 3 MURES BUCCATI, 3, 26 MURIDAE, 3, 4, 12 murinus, Nothocricetulus, 65, 67, 69, 76 MUROIDEA, 4, 20, 21, 26 Mus, 3, 44, 46, 52, 55, 64, 65, 71, 76, 90, 92, 153 Myomorpha, 15, 26 MYOSPALACINAE, 5 myosurus, Nothocricetulus, 67 nanus, Cricetus, 100 Necromys, 44 neglectus, Nothocricetulus, 66, 67, 77 nehringi, Cricetus, 91, 93 Neotoma, 30 NEOTOMINAE, 4, 5 NESOMYIDAE, 3–5 NESOMYINAE, 3 nestor, Tscherskia, 30–32, 35, 37, 38–39 newtoni, Mesocricetus, 4, 9, 10, 13, 16, 112–115, 117, 118, 122, 126–130, 131–133 niger, Cricetus, 92, 92, 103 nigrescens, Cricetulus, 60, 63 nigricans, Cricetus, 90, 92, nigricans, Mesocricetus, 112, 121, 122, 126, 131 nigriculus, Mesocricetus, 4, 112, 120–122, 124, 125, 126 ningshaanensis, Tscherskia, 31, 37, 39, 40, 106, 109 Nothocricetulus, 4–7, 11–16, 18, 20–22, 28, 31, 35, 41, 42, 46, 49, 62, 64, 65–77, 78, 88, 90, 135, 137–139, 144, 153 obscurus, Cricetulus, 4, 44–46, 54–56, 61, 69 obscurus, Necromys, 44 ognevi, Nothocricetulus, 67, 75, 76 Ototylomys, 30 Ourocricetulus, 43, 44, 59 pamirensis, Nothocricetulus, 66, 67, 76 pannonicus, Cricetus, 94 Index to the technical names 181. Panthera, 142 phaeus, Nothocricetulus, 4, 59, 65–67, 69, 75, 76 PHODOPINA, 6, 11, 12, 14, 18, 20, 27, 29, 135–137, 144, 145, 149, 150 Phodopus, 4–7, 11, 12, 14, 17, 18, 20–22, 27, 78, 91, 136, 144, 145, 146–153, 155, 156 planicola, Mesocricetus, 122, 125 polychroma, Cricetus, 93, 94 praedilectus, Phodopus, 145, 149, 150 praeglacialis, Cricetus, 100 przhewalskii, Phodopus, 145, 146, 149, 150 pseudocurtatus, Allocricetulus, 78, 79, 82, 86, 87 pseudogriseus, Cricetulus, 45, 46, 48, 51, 54, 55–56 pulcher, Nothocricetulus, 66, 76 raddei, Mesocricetus, 112–115, 117, 120, 121–126, 127, 130–132 rathgeberi, Mesocricetus, 113 roborovskii, Phodopus, 4, 17, 18, 20, 21, 144, 145–150 Rodentia, 26 rufescens, Cricetus, 91, 93 rusa, Tscherskia, 30 rutilus, Clethrionomys, 142 SIGMODONTINAE, 4, 5, 44 socialis, Microtus, 65 sokolovi, Cricetulus, 5, 11, 14, 42, 43, 47, 49–51, 55, 56–59 songarus, Cricetiscus, 153 SPALACIDAE, 3, 5 Spermophilus, 3, 90 stavropolicus, Cricetus, 93, 101, 103 stoliczkanus, Alticola, 137 sungorus, Cricetiscus, 3, 13, 15, 18, 21, 22, 78, 145, 147, 149–152, 153–155, 156, 157 sviridenkoi, Nothocricetulus, 67, 76 tauricus, Cricetus, 93 tauricus, Nothocricetulus, 66, 76 teilhardi, Allocricetus, 78 tephronotus, Lanius, 142 Theria, 26 tibetanus, Urocricetus, 137–139, 141–143 Tigris, 142 tigris, Panthera, 142 tomensis, Cricetus, 93 triton, Tscherskia, 4, 11, 18, 30, 31–39, 40, 41, 61, 105–108, 137 Tscherskia, 4–7, 11, 12, 14–18, 20, 28, 29, 30–31, 32–41, 42, 61, 68, 78, 105–109, 111, 137 tuvinicus, Cricetiscus, 155, 156 tuvinicus, Cricetulus, 45, 52 TYLOMYINAE, 4, 5 182 TRUE HAMSTERS (CRICETINAE) OF THE PALAEARCTIC REGION. UROCRICETINA, 6, 13, 29, 135, 136, 144 UROCRICETINI, 6, 14, 16–18, 27, 29, 41, 59, 111, 135–136, 144 Urocricetus, 4–6, 9–12, 14, 17, 20, 27, 30, 31, 41, 42, 59, 61, 62, 68, 69, 106, 135, 136–139, 140–143, 152 varians, Cricetinus, 30 variegatus, Cricetus, 92 varius, Cricetus, 92 vernula, Nothocricetulus, 66, 68, 75, 76 vulgaris, Cricetus, 92, 63, 131 xinganensis, Cricetulus, 45, 53 yamashinai, Tscherskia, 32, 39 zvieresombi, Nothocricetulus, 67, 68, 75, 76 TRUE HAMSTERS (CRICETINAE) DOI https://doi.org/ 10.18690/um.fnm.1.2025 OF THE PALAEARCTIC REGION ISBN 978-961-286-940-3 BORIS K 1, RYŠTUFEK , 2 G 3 EORGY I SIDOROVICH S HENBROT 1 Slovenian Museum of Natural History, Vertebrate Department, Ljubljana, Slovenia bkrystufek@pms-lj.si 2 Science and Research Centre Koper, Mediterranean Institute for Environmental Studies, Koper, Slovenia boris.krystufek@zrs-kp.si 3 Ben-Gurion University of the Negev, Jacob Blaustein Institutes for Desert Research, Mitrani Department of Desert Ecology, Beer-Sheva, Israel shenbrot@bgu.ac.il True hamsters are a small subfamily (Cricetinae) containing only 19 species which are endemic Keywords: to the Palaearctic region. Despite such low species richness, general public is well familiar with taxonomy, nomenclature, hamsters, primarily knowing them as pets, experimental laboratory animals and species of morphology, conservation concern. The present work is a compilation integrating achievements of the karyology, molecular systematics, genomic era with the traditional taxonomy. The aim was to provide an authoritative and up-to- species delimitation, date taxonomic guide to the animal group, which is of great interest to experts engaged in subspecies, medical zoology, epidemiology, biostratigraphy, zooarchaeology, evolutionary research, zoogeography, population ecology, animal systematics, biodiversity conservation, museum collection distribution modelling management and many more biological subdisciplines. The most significant original contribution is perhaps revision of the family-group taxa with naming 2 new subtribes and 2 new tribes. The text is supplemented by 120 illustrations and over 700 references. Morphological details of skull and dentition of each of the 19 species are depicted, and their distributions are mapped in detail. The book will allow the user to interpret intelligently the taxonomic system of Cricetinae and to follow taxonomic progress with a critical eye.