Geostiba (Sibiota) recta, 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 : 1103

Geostiba (Sibiota) recta nov.sp. ( Figs 5-14 , Map 1 )

T y p e m a t e r i a l: Holotype 6: "N 42°47'48'' E 42°37'56 (18), GEORGIA: Ratscha, Lentekhi 10 km W, 1160 m, Brachat & Meybohm, 20. V.2016 / Holotypus 6 Geostiba recta sp. n. det. V. Assing 2016" (cAss) . Paratypes: 2♀♀: same data as holotype (cAss) ; 566, 8 ♀♀: " GEORGIA, Caucasus , [4] (Kvemo-Svanetia), N slopes of Svaneti Mts. rng., nr., NW of Tsanashi vill., pitfall traps, sift, 1356 m, 42°48'26.2''N, 42°39'55.9''E, 04.VII.2015 leg. A. Pütz " (cPüt, cAss) ; 1♀: " GEORGIA, Caucasus , [2] ( Kvemo-Svanetia ), Lechkhumi Mts. rng., nr., Sasashi vill., Muashi, pitfall traps, sift, 1390 m, 42°47'20.4''N, 42°59'01.1''E, 01.VII.2015 leg. A. Pütz " (cAss) .

E t y m o l o g y: The specific epithet (Latin, adjective: straight) alludes to the shape of the ventral process of the aedeagus in lateral view.

D e s c r i p t i o n: Body length 2.2-2.7 mm; length of forebody 0.95-1.15 mm. Coloration: body reddish to dark-reddish. Eyes reduced to minute rudiments without pigmentation and without ommatitida. Pronotum without impressions on either side of midline. Hind wings completely reduced. Highly similar to G. bituberculata , except as follows:

6: elytra and tergite VII ( Fig. 9 ) with similar modifications as in G. bituberculata ; posterior margin of tergite VIII broadly and weakly convex; posterior margin of sternite VIII rather strongly convex; median lobe of aedeagus ( Figs 5-8 ) 0.28 mm long, with moderately long and curved flagellum, but without semi-transparent spines in internal sac, with weakly pronounced crista apicalis and crista proximalis; ventral process straight in lateral view; paramere not distinctive.

♀: tergite VIII shaped as in male; posterior margin of sternite VIII ( Fig. 10 ) weakly convex, in the middle shallowly concave; spermatheca minute, maximal extension from apex of distal portion 1.1-1.4 mm distal portion not distinctly dilated and with small conical cuticular invagination, proximal portion not particularly stout, but proximally distinctly dilated.

C o m p a r a t i v e n o t e s: Geostiba recta differs from the highly similar G. bituberculata only by the shape of the male tergite VIII ( G. bituberculata : posterior margin excised in the middle), the morphology of the aedeagus ( G. bituberculata : median lobe 0.30-0.31 mm long; internal sac with longer flagellum; ventral process and crista apicalis of different shape), and by the shape of the spermatheca ( G. bituberculata : spermatheca larger, approximately 0.15 mm long, and of completely different shape, with much stouter and relatively shorter proximal portion). For illustrations of G. bituberculata and allied 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 species was collected in three localities in Ratcha and Kvemo-Svanetia provinces ( Map 1 ), Northwest Georgia, at altitudes of 1160-1390 m. The specimens from Lentekhi were sifted from rhododendron litter on a south slope (MEYBOHM pers. comm.), those from the other locaties were sifted from litter in a montane fir forest and in an old primary beech forest (PÜTZ pers. somm).

Figures

Map 1: Distributions of Geostiba zerchei PACE (white triangle), G. medea PACE (black triangle), and of the species of the G. bituberculatus group: G. recta nov.sp. (white circles), G. largata nov.sp. (black circles), G. artifistula nov.sp. (white asterisk), G. bituberculata (EPPELSHEIM) (black squares), G. kobrisensis PACE (white squares).

Figs 1-14: Geostiba kobrisensis PACE (1-4) and G. recta nov.sp. (5-14): (1-2, 5-8) median lobe of aedeagus in lateral and in ventral view; (3-4, 11-14) spermatheca; (9) median portion of male abdominal tergite VII; (10) female sternite VIII. Scale bars: 0.1 mm.