NEOPERLA OF UNUSUAL SIZE FROM VIETNAM (PLECOPTERA: PERLIDAE)
Bill P. Stark1 and Ignac Sivec2
1 Box 4045, Department of Biology, Mississippi College, Clinton, Mississippi, U.S.A. 39058
E-mail: stark@mc.edu
2 Slovenian Museum of Natural History, Prešernova 20, P.O. Box 290, SLO-1001 Ljubljana, Slovenia
E-mail: isivec@pms-lj.si
ABSTRACT
Two large female specimens, representing a possible undescribed Vietnamese Neoperla species, are described under informal designation and compared to known Vietnamese congeners.
Keywords: Plecoptera, Perlidae, Neoperla, Vietnam, unusual size
INTRODUCTION
Recently, two large perlid specimens belonging to the Smithsonian Institution collection were forwarded to us by a colleague. When casually observed in the vial, these specimens have the general appearance and size of typical Kamimuria or Paragnetina. Surprisingly, both specimens proved to be unusually large Neoperla females, or Neoperla of unusual size (NOUSes), reminding the senior author of The Princess Bride reference to "rodents of unusual size". Currently, the known Vietnamese Neoperla fauna includes 27 named species and two informally designated species known from female specimens (Cao et al. 2007; Stark & Sivec 2008). Most have female forewing lengths in the 10-14 mm range, and the largest are female specimens of N. tamdao Cao & Bae (20.5 mm forewing length), N. yentu Cao & Bae (18.4 mm forewing length), N. nebulosa Stark & Sivec (18 mm forewing length) and N. spinaloba Stark & Sivec (17.5 mm forewing length) (Cao et al. 2007; Stark & Sivec 2008). Because forewing lengths for the new specimens are larger at 23 mm, and the genitalic and egg features differ from known Vietnamese Neoperla, we are providing a description, under informal designation, in order to call attention to this species. All specimens are deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C. (USNM).
RESULTS AND DISCUSSION
Neoperla Vn-C (Figs. 1-7)
Material examined. Vietnam, Cao Bang Province, Phja-Den environs, 948 m, Sante Canopy Malaise traps, 22° 32.433' N, 105° 52.012' E, 25 May-5 June 2011, S.W. Lingafelter, 2? (USNM). Adult habitus. Biocellate. Head patterned with small, dark pigment spots over ocelli and central frons near anterior margin (Fig. 1); occiput, lappets and antennae dark. Pronotum dark brown; femora banded with pale basal third and dark apical region, tibiae and tarsi dark brown. Wing membrane and veins dark brown to black, except pale costal margin and crossveins.
Female. Forewing length 23 mm. Subgenital plate a small, apically notched, sclerotized, median projection (Fig. 2). Vagina relatively long and slender, slightly wider anteriorly (Fig. 3); Spermathecal stalk slender, expanded into a hook shaped chamber.
Egg. Barrel shaped (Fig. 4). Length ca. 325-340 ^m; collar width ca. 66-72 ^m; equatorial width ca. 206216 ^m. Collar sessile without flange and surrounded by two rows of irregular follicle cell impressions; anchor flat, disc shaped with irregular
Figs. 1-3. Neoperla Vn-C female structures. 1. Head and pronotum. 2. Subgenital plate. 3. Vagina and spermatheca.
Figs. 4-7. Neoperla Vn-C egg structures. 4. Entire egg. 5. Collar detail. 6. Follicle cell impression detail on lid. 7. Lid detail.
margin. Most of chorionic surface covered with closely packed slender striae in groupings of four (Figs. 4-5, 7); outer striae of each group slightly thicker and significantly raised at collar end (Figs. 5, 7); width of strial groupings ca. 16.9-18.3 ^m near lid. Lid bears two distinct rows of follicle cell impressions near juncture with striae, and ca. 3 progressively less distinct follicle cell impression rows (Figs. 6-7); follicle cell impression floors filled with minute punctations. Micropyles subequatorial. Diagnosis. Spermathecal structure indicates this species is a member of the Montivaga Group as designated by Zwick (1983, 1986). This group includes 16 of the known Vietnamese species and all those in which female forewing length exceeds 16 mm. The subgenital plate of this species is generally similar to those of N. idella Stark & Sivec, 2008, N. mnong Stark, 1987 and N. yao Stark, 1987, and the egg is similar to those of N. hubleyi Stark & Sivec, 2008, N. idella and N. spinaloba Stark & Sivec, 2008. Although this species shares several characters with N. idella, the two differ, particularly in lid chorionic surface (Figs. 6-7), where N. idella has an irregular row of large pits surrounding the lid along the strial margin, and no conspicuous follicle cell impressions occur on the lid (see Fig. 102 in Stark & Sivec 2008). Comments. Based on similarities in size, color pattern and proximity these large females may represent the unknown female stage for N. dao Stark & Sivec 2008, a species described from Tam Dao Hill Station, Vihn Phu province. Male forewing length for N. dao is 16 mm which might be compatible with the 23 mm forewing length of the new specimens. However, we hesitate to make the association until co-occurrence is established.
Stark, B.P. 1987. Records and descriptions of Oriental Neoperlini (Plecoptera: Perlidae). Aquatic Insects, 9:45-50.
Stark, B.P. & I. Sivec. 2008. New species and records of Neoperla (Plecoptera: Perlidae) from Vietnam. Illiesia, 4:19-54.
Zwick, P. 1983. The Neoperla of Sumatra and Java (Indonesia) (Plecoptera: Perlidae). Spixiana, 6:167204.
Zwick, P. 1986. The Bornean species of the stonefly genus Neoperla (Plecoptera: Perlidae). Aquatic Insects, 8:1-53.
Received 29 November 2011, Accepted 8 December 2011, Published 13 December 2011
ACKNOWLEDGMENTS
We thank Dr. Boris Kondratieff for forwarding the specimens on which this report is based. We also thank Dr. David Miller, Dr. Frank Hensley, and the daughters of B.P. Stark, Rene Roberts and Edith Kennedy, for their help in clarifying the literary reference from The Princess Bride.
REFERENCES
Cao, T.K.T., S.A. Ham, & Y.J. Bae. 2007. Description of three new species of Neoperla (Plecoptera: Perlidae) and a historical review of tropical Southeast Asian Perlidae. Zootaxa, 1453:41-54.