Geostiba (Sibiota) artifistula, 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 : 1104-1106

Geostiba (Sibiota) artifistula nov.sp. ( Figs 26-31 , Map 1 )

T y p e m a t e r i a l: Holotype 6: " GEORGIA, Caucasus, [5] (Ratcha), S slopes of Letchkhumskiy Mts. rng., env. of NW of Likheti vill., pitfall traps, sift, 42°35'32.0''N, 43°13'34.9''E, 763 m, 04.VII.2015 leg. A. Pütz / Holotypus 6 Geostiba artifistula sp. n. det. V. Assing 2016" (cAss). Paratypes: 266, 3 ♀♀: same data as holotype (cPüt, cAss).

E t y m o l o g y: The specific epithet is a noun in apposition and composed of the Latin adjective artus (narrow) and the Latin noun fistula (pipe, hose). It alludes to the weakly dilated distal portion of the spermathecal duct, one of the characters distinguishing this species from the similar and geographically close G. recta .

D e s c r i p t i o n: Body length 2.7-3.1 mm; length of forebody 1.05-1.20 mm. Coloration: body reddish to dark-reddish. Eyes reduced to minute rudiments without pigmentation and without ommatitida. Pronotum ( Fig. 26 ) without impressions on either side of midline. Hind wings completely reduced. Highly similar to the geographically close G. recta and G. largata .

6: elytra ( Fig. 27 ) as in G. recta and G. largata ; tergite VII with the pair of carinae very narrow and of variable length; posteror margin of tergite VIII with small and shallow median excision; posterior margin of sternite VIII rather strongly convex; median lobe of aedeagus ( Figs 28-29 ) approximately 0.3 mm long, without distinct flagellum and without semi-transparent spines in internal sac; ventral process apically very slender in lateral view; paramere not distinctive.

♀: tergite VIII with broadly and weakly convex posterior margin without median excision; posterior margin of sternite VIII broadly and very shallowly concave in the middle; spermathecal capsule ( Figs 30-31 ) with weakly dilated distal portion, with very flat and small apical cuticular invagination, and with rather short and not distinctly dilated proximal portion.

C o m p a r a t i v e n o t e s: This species is distinguished from the similar and geographically close G. largata and G. recta by the narrower carinae on the male tergite VII, the larger median lobe with an apically more slender ventral process (lateral view) and by the different shape of the spermatheca (flat and small apical cuticular invagination; shape of distal portion of capsule; indistinctly dilated proximal portion), from G. recta additionally by the absence of a distinct flagellum in the internal sac of the aedeagus.

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 is situated in the Letchkhumskiy range ( Map 1 ), Ratcha province, Northwest Georgia, at an altitude of approximately 760 m. The specimens were sifted from leaf litter in a young secondary mixed forest (PÜTZ pers. comm.).

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 26-31: Geostiba artifistula nov.sp.: (26) male forebody; (27) male elytra; (28-29) median lobe of aedeagus in lateral and in ventral view; (30-31) spermatheca. Scale bars: 26: 0.2 mm; 27-31: 0.1 mm.