Geostiba (Sibiota) unicuneata, 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 : 1113-1114

Geostiba (Sibiota) unicuneata nov.sp. ( Figs 63-70 , Map 2 )

T y p e m a t e r i a l: Holotype 6: " ARMENIA, above Jermuk , sifting of plant leavings near snow residues, 2400 m, 39.839053N 45.693496E, 21.V.2015 M. Kocian lgt. / Holotypus 6 Geostiba unicuneata sp. n. det. V. Assing 2016" (cAss) . Paratypes: 566, 10 ♀♀: same data as holotype (cKoc, cAss) ; 16, 3♀♀: ARMENIA [AR16-11] ca. 50 km NW Sisian, Jermuk , 39°50'02''N, 45°40'21''E, 2110 m, oak forest and forest margin, litter and roots sifted, 30.VI.2016, leg. M. Schülke " ( MNB, cAss); 1♀: " ARMENIA [AR16-11b] ca 50 km NW Sisian, Jermuk, 39°50'02''N, 45°40'21''E, 2110 m, oak forest, litter and roots sifted, 12.VII.2016, leg. M. Schülke " ( MNB) .

E t y m o l o g y: The specific epithet is an adjective composed of the Latin numeral unus and an adjective derived from the Latin noun cuneus (wedge). It alludes to the conspicuous wedge-shaped median elevation on the male tergite VII.

D e s c r i p t i o n: Body length 2.1-2.5 mm; length of forebody 0.9-1.1 mm. Coloration and other characters as in G. unituber , except as follows:

Pronotum without impression on either side of midline.

6: elytra ( Figs 63-64 ) with narrow, anteriorly strongly elevated and broader carina extending along whole suture, disc with extensive, but shallow impression, punctation shallow and sparse, not granulose; abdominal tergite VII ( Figs 65-66 ) with a conspicuous, long and strongly elevated, wedge-shaped (lateral view), and dorsally sharp median elevation; posterior margins of tergite VIII convex; posterior margin of sternite VIII indistinctly angled in the middle; median lobe of aedeagus ( Figs 67-68 ) 0.22 mm long, without semi-transparent spines in internal sac; ventral process stout and nearly straight in lateral view; paramere not distinctive.

♀: tergite VIII with convex posterior margin; posterior margin of sternite VIII broadly and weakly convex; spermathecal capsule ( Figs 69-70 ) with weakly dilated distal portion and moderately stout, twisted proximal portion.

C o m p a r a t i v e n o t e s: Geostiba unicuneata is distinguished from all its congeners particularly by the shape of the postero-median elevation on the male tergite VII, as well as by the primary sexual characters. It additionally differs from its Armenian consubgeners by the absence of distinct impressions on the pronotum.

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 material was collected in two close localities near Jermuk, South Armenia ( Map 2 ). The specimens from the type locality were sifted from debris near snow fields at an altitude of 2400 m, those from the second locality were sifted from leaf litter and roots in an oak forest at an altitude of 2110 m. For an illustration of the latter locality see ASSING (2016b: figure 43).

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 63-70: Geostiba unicuneata nov.sp.: (63) male forebody; (64) male elytra; (65) male abdominal segments VI-VIII in dorsal view; (66) male tergites VII-VIII in lateral view; (67-68) median lobe of aedeagus in lateral and in ventral view; (69-70) spermatheca. Scale bars: 63-66: 0.2 mm; 67-70: 0.1 mm.