NATURA SLOVENIAE 19(2): 5-14 Prejeto / Received: 13.11.2017 
SCIENTIFIC PAPER Sprejeto / Accepted: 5.12.2017 
Biotehniška fakulteta Univerze v Ljubljani in Nacionalni inštitut za biologijo, Ljubljana, 2017 
 
 
 
First discoveries of colonies of the rare ant species 
Camponotus tergestinus Müller, 1921 (Hymenoptera: 
Formicidae) in situ 
 
 
 
Gregor BRAČKO 
 
 
University of Ljubljana, Biotechnical Faculty, Department of Biology, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia;  
E-mail: gregor.bracko@bf.uni-lj.si 
 
 
 
Abstract. The rare ant species Camponotus tergestinus Müller, 1921 has so far been reported from few 
central and southern European localities, but none of its colonies have ever been recorded in situ. In 2016 and 
2017, two colonies were found at Lipica (SW Slovenia), the first nesting on Quercus pubescens at the height of 
3.2 m, the second on Q. cerris at the height of 2.2 m. Both nests had two entrances each. Numerous visits have 
been carried out at the site in order to observe both colonies. Based on available data, Camponotus tergestinus is 
an arboricolous species having a strong association with oaks. Its arboricolous and presumably nocturnal habits 
could be the main reasons for the paucity of available data. A list of all known localities, retrieved from both 
published and unpublished records, is also provided. 
 
Key words: ants, Camponotus tergestinus, Quercus, nest, behaviour, distribution, Slovenia 
 
 
Izvleček. Prva odkritja kolonij redke vrste mravlje Camponotus tergestinus Müller, 1921 
(Hymenoptera: Formicidae) in situ – Redka vrsta mravlje Camponotus tergestinus Müller, 1921 je bila doslej 
najdena na maloštevilnih lokalitetah v srednji in južni Evropi, a doslej ni bila najdena še nobena kolonija in situ.  
V letih 2016 in 2017 smo našli dve koloniji v Lipici (JZ Slovenija). Prva je imela mravljišče na puhastem hrastu 
(Quercus pubescens) na višini 3,2 m, druga na ceru (Q. cerris) na višini 2,2 m. Obe mravljišči sta imeli po dva 
vhoda. Opravili smo več obiskov lokalitete z namenom opazovanja obeh kolonij. Na podlagi razpoložljivih 
podatkov lahko domnevamo, da je Camponotus tergestinus drevesna vrsta, ki je močno povezana s hrasti. 
Drevesni in domnevno nočni način življenja je verjetno glavni razlog za majhno število razpoložljivih podatkov. 
Pripravili smo tudi seznam vseh znanih lokalitet, pridobljen iz objavljenih in neobjavljenih podatkov. 
 
Ključne besede: mravlje, Camponotus tergestinus, Quercus, mravljišče, vedenje, razširjenost, Slovenija 
Gregor BRAČKO: First discoveries of colonies of the rare ant species Camponotus tergestinus... / SCIENTIFIC PAPER 
NATURA SLOVENIAE 19(2): 5-14 
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Introduction 
 
 
Camponotus Mayr, 1861 is the second most speciose ant genus in Europe, containing  
58 species (Czechowski et al. 2012). Most Camponotus species occurring in Central Europe 
have relatively well known biology and distribution (Seifert 2007, Markó et al. 2009, 
Czechowski et al. 2012, Wagner 2014). One exception is Camponotus tergestinus  
Müller, 1921, a rarely collected taxon, whose ecology and life-history are almost unknown. 
Müller (1921) described a worker from Coloncovez near Trieste (Italy) and a queen from 
nearby Lipica (Slovenia). Subsequently, the species was only sporadically reported from some 
central and southern European countries (Menozzi 1928, Agosti & Collingwood 1987, Ionescu-
Hirsch et al. 2009, Ješovnik et al. 2011, Lapeva-Gjonova & Kiran 2012, Wiezik & Wieziková 
2013). Usually, only single specimens were found at each locality or reported from collections. 
So far, only two colonies were discovered, but not in situ. Müller (1921) found a hibernating 
colony in oak wood brought as firewood to the Trieste Museum from Coloncovez. In the 
second case, C. tergestinus was found in the Port of Haifa (Israel) in a container with oak logs 
from Plopeni (Romania) (Ionescu-Hirsch et al. 2009). Consequently, it was presumed that this 
species is associated with oak forests and nests in wood in the tree canopies (Ionescu-Hirsch 
et al. 2009, Wiezik & Wieziková 2013), although no colonies were found in living trees. 
 
Here we report on the first discovery of two arboricolous colonies of C. tergestinus from 
Lipica in southwestern Slovenia, as well as on our observations carried out during multiple 
visits to the site in 2016 and 2017. Also, we list all known localities of C. tergestinus, retrieved 
from both published and unpublished records. 
 
 
 
Materials and methods 
 
 
In 2016, we were performing a general inventory of the ant fauna in the area of Lipica 
(southwestern Submediterranean Slovenia). The area is covered by thermophilous meadows 
and pastures with scattered oaks, Submediterranean karst forest and scrub. After our finding 
of some Camponotus tergestinus workers on a tree, we repeatedly visited the site in 2016 and 
2017. We discovered the C. tergestinus colonies by climbing the tree with a ladder and 
following any detectable worker. Later, we performed further observations of the colonies 
from a distance of at least two metres to prevent ants from seeing us. During our visits we 
also looked for other ant species living in the same tree. 
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Results 
 
Overview of all Camponotus tergestinus records 
 
So far, C. tergestinus is known from 13 localities (Tab. 1, Fig. 1). The records from Lipica 
include a queen (Müller 1921) and the two colonies mentioned in the present paper. 
 
Table 1. All known records of Camponotus tergestinus. 
Tabela 1. Vsi znani podatki za vrsto Camponotus tergestinus. 
Site Country Reference 
Coloncovez near Trieste Italy Müller 1921 
Lipica Slovenia 
Müller 1921 
new records 
Bologna Italy Menozzi 1928 
Turkish Thrace Turkey Agosti & Collingwood 1987 
Fóti Somlyó Mt. Hungary Ionescu-Hirsch et al. 2009 
Plopeni (Prahova County) Romania Ionescu-Hirsch et al. 2009 
Cetăţuia (Tulcea County) Romania Ionescu-Hirsch et al. 2009 
Nera Valley near Damian  
(Caraş-Severin County) 
Romania Ionescu-Hirsch et al. 2009 
Paklenica National Park Croatia Ješovnik et al. 2011 
Sinemorets (Tsarevo district) Bulgaria Lapeva-Gjonova & Kiran 2012 
Štiavnické vrchy Mts. Slovakia Wiezik & Wieziková 2013 
Camigliatello Silano (Calabria) Italy unpublished record, F. Rigato,  
pers. comm. 2017 
Antalya Turkey unpublished record from ant collection of  
Cedric Collingwood, stored in National 
Museums Liverpool 
 
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NATURA SLOVENIAE 19(2): 5-14 
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Figure 1. Known records of Camponotus tergestinus (Lipica is marked with a star, an unspecified locality from Turkish 
Thrace with a rectangle). 
Slika 1. Znani podatki o vrsti Camponotus tergestinus (Lipica je označena z zvezdo, nespecificirana lokaliteta iz Turške 
Trakije pa s kvadratom). 
 
 
Description of C. tergestinus nest sites from Lipica 
 
On 21. 5. 2016 we discovered some C. tergestinus workers walking on the branch of a 
pubescent oak (Quercus pubescens). The oak was approximately 12 m high, standing isolated 
in a karst meadow near the entrance to the Lipica Stud Farm estate, 45°39.62'N, 13°53.46'E, 
410 m a.s.l. Since we could not find any C. tergestinus nest, we revisited the site on  
18. 7. 2016 and discovered a colony (colony A) in a burl on one of oak's four main branches at 
the height of 3.2 m (Fig. 2A). The nest had two entrances 15 cm apart and with diameter of 
approximately 5 mm each (Fig. 3A). 
 
On 17. 5. 2017, while inspecting several other oaks in the area, we found another colony 
of C. tergestinus (colony B) nesting on a Turkey oak (Quercus cerris) inside the Lipica Stud 
Farm estate, 45°39.69'N, 13°53.44'E, 410 m a.s.l., 150 m from colony A. The tree was 
approximately 15 m high, standing in the meadow/pasture with other scattered oaks. The nest 
Gregor BRAČKO: First discoveries of colonies of the rare ant species Camponotus tergestinus... / SCIENTIFIC PAPER 
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was located in a tree knot on the trunk at the height of 2.2 m (Fig. 2B). As in the case of 
colony A, the nest had two entrances 3 cm apart and with diameters of 6 mm and 3 mm, 
respectively (Fig. 3B). 
 
 
 
Figure 2. Position of the nests of Camponotus tergestinus colonies from Lipica (pointed by an arrow): A – colony A nest 
on Quercus pubescens, B – colony B nest on Quercus cerris. 
Slika 2. Položaj mravljišč kolonij Camponotus tergestinus iz Lipice (označen s puščico): A – mravljišče kolonije A na 
Quercus pubescens, B – mravljišče kolonije B na Quercus cerris. 
 
 
Figure 3. Nest entrances of Camponotus tergestinus colonies from Lipica (pointed by arrows): A – one of the two nest 
entrances of colony A, B – the two nest entrances of colony B. 
Slika 3. Vhodi mravljišč kolonij Camponotus tergestinus iz Lipice (označeni s puščicami): A – eden od dveh vhodov 
mravljišča kolonije A, B – vhoda mravljišča kolonije B. 
 
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Observations of C. tergestinus colonies 
 
We visited and observed both colonies several times (Tab. 2). 
 
Table 2. Observations of C. tergestinus colonies from Lipica. 
Tabela 2. Opazovanja kolonij C. tergestinus iz Lipice. 
Date Time period Weather 
conditions 
Colony Notes 
21.5.2016 afternoon sunny,  
T 23°C–24°C 
A few individual workers were spotted in the 
tree 
18.7.2016 morning sunny,  
T 27°C–29°C 
A nest discovered 
1.10.2016 12h–13h changeable 
cloudy,  
T around 20°C 
A one worker outside the nest 
1.5.2017 11h–12h sunny, T 18°C A no workers in the tree; later, some came 
out lured with a blade of straw (Fig. 4) 
17.5.2017 16h–17h changeable 
cloudy and 
windy, T 22°C 
A 4 workers leaving/entering the nest 
to/from the upper parts of the tree 
17.5.2017 afternoon mostly sunny 
and windy,  
T 21°C 
B nest discovered 
30.5.2017 8.45h–9.45h sunny,  
T 24°C–25°C 
A 16 workers leaving/entering the nest, all 
but one to/from the upper parts of the tree 
30.5.2017 10.15h–11.15h sunny,  
T 25°C–26°C 
B 4 workers leaving/entering the nest 
to/from the upper parts of the tree 
30.5.2017 15h–16h sunny,  
T 26°C–27°C 
A 6 workers leaving/entering the nest 
to/from the upper parts of the tree 
30.5.2017 16.30h–17.30h sunny,  
T 27°C 
B one worker entering the nest from upper 
parts of the tree 
27.7.2017 14h–15h sunny,  
T around 28°C 
A one worker entering the nest from upper 
parts of the tree 
23.9.2017 11h–12h changeable 
cloudy,  
T around 19°C 
A no workers in the tree 
4.10.2017 16.30h–17.30h mostly sunny, 
18°C–19°C 
A one worker leaving the nest to the upper 
parts of the tree 
4.10.2017 20h–21h 
(night 
observation) 
14°C–15°C A some 30 workers outside the nest, most of 
them descending to the height of about 
half a metre; then going to the contiguous 
main branch where they were directed to 
the upper parts of the tree; five workers 
were carrying nestmates (adult transport) 
 
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Figure 4. Camponotus tergestinus workers of colony A after being lured out from the nest with a blade of straw (on the 
left a Crematogaster schmidti worker is also visible). 
Slika 4. Delavke Camponotus tergestinus iz kolonije A, potem ko smo jih izvabili iz mravljišča s slamico (na levi je vidna 
tudi delavka Crematogaster schmidti). 
 
 
The following ant species were found in oaks with C. tergestinus colonies: Camponotus 
aethiops (Latreille, 1798), C. fallax (Nylander, 1856), C. piceus (Leach, 1825), Colobopsis 
truncata (Spinola, 1808), Crematogaster schmidti (Mayr, 1853), Dolichoderus quadripunctatus 
(Linnaeus, 1771), Formica gagates Latreille, 1798, Lasius paralienus Seifert, 1992, 
Temnothorax affinis (Mayr, 1855), T. crassispinus (Karavaiev, 1926), T. italicus (Consani & 
Zangheri, 1952) and T. jailensis (Arnoldi, 1977) in the oak with colony A, and Camponotus 
ligniperda (Latreille, 1802), Crematogaster schmidti, Formica cunicularia Latreille, 1798,  
F. fusca Linnaeus, 1758, Temnothorax affinis, T. jailensis and T. tergestinus (Finzi, 1928) in 
the oak with colony B. C. schmidti was the commonest species in both trees with some 
separate trails leading along the branches. One trail was just few cm from one of the 
entrances of C. tergestinus colony A. 
 
 
 
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NATURA SLOVENIAE 19(2): 5-14 
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Discussion 
 
 
The rediscovery of the rare ant species C. tergestinus at Lipica is important because it has 
allowed the first observations of its colonies in nature (in situ). C. tergestinus is an 
arboricolous species, nesting in trunk cavities or large branches in the tree canopy, as already 
indicated by other authors (Wiezik & Wieziková 2013). As it nests and forages in trees, it can 
be defined as a true arboricolous species (Seifert 2008). Moreover, we assume that  
C. tergestinus is associated with oaks. Oaks are constantly reported in relation to previous 
records of C. tergestinus (Müller 1921, Ionescu-Hirsch et al. 2009, Lapeva-Gjonova & Kiran 
2012, Wiezik & Wieziková 2013). One exception is the record of a single specimen from 
Paklenica NP (Croatia), where a beech forest is mentioned as habitat (Ješovnik et al. 2011). It 
is quite possible, however, that this specimen of C. tergestinus was accidentally collected in a 
lower section of the Park, where oaks are more common (A. Ješovnik & M. Zec, pers. comm. 
2017). In general, different Quercus species, especially old trees with rough bark and cavities, 
are preferentially inhabited by several other arboricolous ant species, e.g. Camponotus fallax, 
Colobopsis truncata, Dolichoderus quadripunctatus, Temnothorax affinis, T. corticalis 
(Schenck, 1852) (Buschinger 1993, Seifert 2007, 2008). Based on the present and previous 
findings, C. tergestinus can be considered a thermophilous species, preferring warm habitats 
where oaks are present. 
 
On the basis of known records, C. tergestinus has a relatively large distribution, from 
Central Europe (Slovakia and Hungary) to southern Italy (Calabria) and southeastern Balkan 
Peninsula (Turkish Thrace), and even further to Anatolia (Antalya). It looks quite strange that 
despite its large distribution so few records of this species are known. C. tergestinus is 
certainly not as common as some other arboricolous species occurring in the same regions 
(e.g. Camponotus fallax, Colobopsis truncata, Temnothorax affinis). The reasons could be low 
competitiveness in comparison to similar species and a narrower ecological niche. 
Nevertheless, one of the main reasons for the paucity of records is probably its arboricolous 
lifestyle. Arboricolous species are often underrated in faunistic surveys due to their difficult 
detectability and lack of target sampling methods (Wagner et al. 2011). Being a true 
arboricolous species, C. tergestinus activity is restricted to trees, and normally it avoids 
foraging near the ground, as could have been concluded from our observation on 30. 5. 2017; 
consequently, it can hardly be seen by any researcher. In addition, our observations showed 
that in the daytime C. tergestinus is quite inconspicuous, with individually foraging workers 
that mostly leave nest in low numbers. On few occasions actually no ants were seen outside 
the nest, although workers of other species (e.g. Crematogaster schmidti, Camponotus fallax, 
Colobopsis truncata, Dolichoderus quadripunctatus, Formica gagates) were active. According 
to the number of workers detected outside the nest, the situation was very different in the 
nocturnal observation of 4. 10. 2017, when colony A was more active than during all our 
previous visits. Although only a single nocturnal observation was carried out, this one could 
indicate C. tergestinus having its peak of activity by night. That could be a further reason for 
the paucity of records. 
 
The rediscovery of C. tergestinus at Lipica, after almost a century (Müller 1921), indicates 
that species might not be rare in this region. The discovery of further colonies could reveal 
new details about the biology of this enigmatic species. 
Gregor BRAČKO: First discoveries of colonies of the rare ant species Camponotus tergestinus... / SCIENTIFIC PAPER 
NATURA SLOVENIAE 19(2): 5-14 
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Povzetek 
 
 
Med mravljami iz rodu Camponotus, ki so razširjene tudi v srednji Evropi, je vrsta C. tergestinus ena 
najmanj poznanih. O njej imamo podatke z maloštevilnih lokalitet, pri čemer tu prvič navajamo dve še 
neobjavljeni lokaliteti (J Italija in Antalija). Doslej so bile v večini primerov najdene le posamezne delavke, 
kolonije pa le v dveh primerih, a ne in situ. Potem ko je Müller (1921) opisal matico C. tergestinus iz 
Lipice, smo tu vrsto leta 2016 in 2017 ponovno odkrili. Našli smo dve koloniji, ena je imela mravljišče na 
eni od glavnih vej puhastega hrasta (Quercus pubescens) na višini 3,2 m, druga pa na deblu cera  
(Q. cerris) na višini 2,2 m, obe mravljišči pa sta imeli po dva vhoda. Gre za prvo dokumentirano najdbo 
kolonij te vrste in situ. V omenjenih dveh letih smo koloniji večkrat opazovali. Dostikrat smo opazili le malo 
ali nobene delavke obravnavane vrste, čeprav so bile takrat na istem drevesu mravlje drugih vrst aktivne 
(npr. Crematogaster schmidti, Camponotus fallax, Colobopsis truncata, Dolichoderus quadripunctatus, 
Formica gagates). Kadar so bile delavke C. tergestinus zunaj mravljišča, so v večini primerov prihajale 
oziroma so odhajale navzgor proti višjim delom drevesa. Opravili smo tudi eno nočno opazovanje in takrat 
je bilo število delavk zunaj mravljišča najvišje izmed vseh opazovanj. C. tergestinus je po vsej verjetnosti 
prava drevesna vrsta, ki poseljuje termofilne habitate s hrastom, na katere je, kot kaže, močno vezana. 
Eden izmed glavnih razlogov, da je kljub relativno velikemu območju razširjenosti, ki sega od srednje 
Evrope do južne Italije in Balkana ter celo v Anatolijo, o tej vrsti tako malo podatkov, je njen drevesni 
način življenja. Delavke se večinoma zadržujejo v višjih predelih dreves in so tako težje dostopne pri 
vzorčenjih. Dodatni razlog je, da so, kot kaže, bolj aktivne v nočnem času. Predvidevamo, da  
C. tergestinus na obravnavanem območju ni redka. 
 
 
 
Acknowledgements 
 
 
I am grateful to Fabrizio Rigato (Museo di Storia Naturale, Milano, Italy) for an unpublished record of this species 
from Italy and to Tony Hunter (National Museums Liverpool, UK) for the information about the C. tergestinus stored in 
NML. I thank Ana Ješovnik and Mate Zec (Zagreb, Croatia) for their data about the finding of C. tergestinus in the 
Paklenica NP. I am indebted to Tina Čič and Simon Rojc (Lipica Stud Farm, Slovenia) for allowing me to inspect the trees 
inside the Lipica estate. Last but not least, I thank Maja Zagmajster (University of Ljubljana, Slovenia) for her useful 
comments. 
 
 
 
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