Geostiba (Sibiota) unituber, Assing, 2016

Assing, Volker, 2016, A revision of Geostiba of the West Palaearctic region. XXIII. On the Sibiota species of the Caucasus region exclusive of Turkey (Coleoptera: Staphylinidae: Aleocharinae), Linzer biologische Beiträge 48 (2), pp. 1097-1117 : 1108-1109

Geostiba (Sibiota) unituber nov.sp. ( Figs 32-41 , Map 2 )

T y p e m a t e r i a l: Holotype 6: " ARMENIA [4] - N Yerevan, NW Hrazdan, 40°41'40''N, 44°29'16''E, 2500 m, W-slope, sifted, 26.VI.2016, V. Assing / Holotypus 6 Geostiba unituber sp. n. det. V. Assing 2016" (cAss) . Paratypes: 366, 9 ♀♀: same data as holotype (cAss) ; 466, 6 ♀♀: same data as holotype, but leg. Schülke ( MNB) .

E t y m o l o g y: The specific epithet is a noun in apposition composed of the Latin numeral unus (one) and the Latin noun tuber (bump, protuberance). It alludes to the presence of a median tubercle (as opposed to a pair of carinae) on the male tergite VII.

D e s c r i p t i o n: Body length 2.2-2.5 mm; length of forebody 0.85-1.00 mm. Coloration: body yellowish to pale reddish-yellow. Eyes strongly reduced, with weak pigmentation and composed of approximately five ommatitida. Pronotum with a more or less pronounced longitudinal impression on either side of midline ( Fig. 32 ). Hind wings completely reduced.

6: elytra ( Fig. 32 ) with narrow, anteriorly slightly broader carina extending along whole suture, disc with usually extensive and more or less pronounced impression, punctation very fine, barely noticeably granulose; abdominal tergite VII ( Figs 33-35 ) with a rather broad, but variably shaped median tubercle posteriorly, upper surface of this tubercle glossy, flat or weakly excavate; posterior margins of tergite VIII and sternite VIII broadly convex; median lobe of aedeagus ( Figs 36-38 ) 0.24 mm long, without semitransparent spines in internal sac; ventral process weakly curved in lateral view; paramere not distinctive.

♀: elytra and abdominal tergite VII without modifications; tergite VIII shaped as in male; posterior margin of sternite VIII weakly convex; spermathecal capsule ( Figs 39- 40 ) with dilated distal portion and rather stout and short proximal portion.

C o m p a r a t i v e n o t e s: Geostiba unituber is characterized by the shape of the median tubercle on the male tergite VIII, the morphology of the aedeagus, and the shape of the spermatheca. From most Georgian Sibiota species, it is additionally distinguished by paler coloration and less reduced eyes. For illustrations of the sexual characters of the previously described Caucasian Sibiota species see ASSING (2005, 2009, 2011, 2016a) and PACE (1996).

D i s t r i b u t i o n a n d n a t u r a l h i s t o r y: The type locality ( Fig. 41 ) is situated in the Pambaki range some 55 km to the north of Yerevan, North Armenia ( Map 2 ). The specimens were sifted from leaf litter and the roots of grass on a slope with scattered Salix sp. at an altitude of 2500 m.

Figures

Map 2: Distributions of the species of the G. carinicollis group: G. articarinata ASSING (black square), G. convergens ASSING (white square), G. uniplicata ASSING (black diamond), G. krzysztofi (ROUBAL) (white diamonds), G. carinicollis (EPPELSHEIM) (white circles), G. unituber nov.sp. (black circle), G. pambakica nov.sp. (white triangles), G. unicuneata nov.sp. (black star), G. meghruica nov.sp. (white star).

Figs 32-40: Geostiba unituber nov.sp.: (32) male pronotum and elytra; (33-35) median portion of male tergite VII; (36-38) median lobe of aedeagus in lateral and in ventral view; (39-40) spermatheca. Scale bars: 0.1 mm.

Fig. 41: Type locality of Geostiba unituber nov.sp.