Geostiba (Sibiota) largata, 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 : 1103-1104

Geostiba (Sibiota) largata nov.sp. ( Figs 15-25 , Map 1 )

T y p e m a t e r i a l: Holotype 6: "N 42°23'11 E 42°56'42 (13), GEORGIA: Imereti, Nakerala 6 km W, 1450 m, Brachat & Meybohm, 17.V.2016 / Holotypus 6 Geostiba largata sp. n. det. V. Assing 2016" (cAss) . Paratypes: 466, 7 ♀♀: same data as holotype (cAss, MNB) ; 566, 4 ♀♀: "N42°23'48' E43°01'59 (14), GEORGIA: Ratscha, Nakerala 4 km N, 1150 m, Brachat & Meybohm, 18.V.2016 " (cAss, MNB); 2♀♀: "N 42°22'37 E 43°02'28 (15), GEORGIA: Ratscha, Nakerala Pass 1260 m, Brachat & Meybohm, 18.V.2016 " (cAss, MNB); 16, 4♀♀: "N 42°22'20 E 43°02'30 (21), GEORGIA: Ratscha, Nakerala Pass, 1320 m, Brachat & Meybohm, 22.V.2016 " (cAss); 266, 3♀♀: "N 42°22'39 E 43°02'22 (22), GEORGIA: Ratscha , Nakerala Pass , 1220 m, Brachat & Meybohm, 22.V.2016 " (cAss); 16: "N 42°29'10 E 43°06'06 (23), GEORGIA: Ratscha , Nikortsminda 4 km NW, 1395 m, Brachat & Meybohm, 23.V.2016 " (cAss); 566, 4 ♀♀: " GEORGIA, Caucasus , [8] ( Ratcha ), Ratschinskyi Mts. rng., 5 km NW, Nakerala pass, nr. Tkibili town , pitfall traps, sift, 42°23'08.1''N, 42°58'46.67''E, 1440 m, 06.VII.2015 leg. A. Pütz " (cPüt, cAss) .

E t y m o l o g y: The specific epithet is the past participle of the Latin verb largare (to enlarge) and alludes to the strongly dilated distal portion of the spermathecal capsule.

D e s c r i p t i o n: Body length 2.2-3.0 mm; length of forebody 1.0- 1.2 mm. Habitus as in Fig. 15 . Coloration: body reddish to dark-reddish. Eyes reduced to minute rudiments without pigmentation and without ommatitida. Pronotum ( Fig. 16 ) without impressions on either side of midline. Hind wings completely reduced. Highly similar to G. bituberculata , except as follows:

6: elytra ( Fig. 17 ) (in large males!) with broader and coarsely granulose sutural elevations, these elevations much broader and more pronounced near scutellum than in posterior portion of suture; tergite VII with pair of posteriorly converging carinae of variable length and shape (sharply keeled to convex in cross-section), this pair of carinae practically obsolete in small males; posterior margin of tergite VIII convex, with or without small and shallow median excision; posterior margin of sternite VIII rather strongly convex; median lobe of aedeagus ( Figs 18-22 ) approximately 0.27 mm long, without distinct flagellum and without semi-transparent spines in internal sac; paramere not distinctive.

♀: tergite VIII with broadly and weakly convex posterior margin without median excision; posterior margin of sternite VIII broadly and shallowly concave in the middle; spermathecal capsule ( Figs 23-25 ) with strongly dilated distal portion, with a very broad and flat apical cuticular invagination, and with a relatively short, 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 G. bituberculata and G. recta , the geographically closest representatives of the G. bituberculata group, by the modifications of the male elytra, by the shape of the ventral process of the aedeagus (lateral view), by the absence of a distinct flagellum in the internal sac of the aedeagus, by the posteriorly distinctly concave female sternite VIII, and by the shape of the spermatheca, especially the much more strongly dilated distal portion of the capsule.

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: Thespecimenswerecollected in several localities in the environs of the Nakerala pass ( Map 1 ), Imereti and Ratcha provinces, Northwest Georgia, at altitudes of 1150-1450 m. They were sifted from leaf litter in a mixed primary forest (fir, beech) with rhododendron, in a beech forest, in a secondary mixed deciduous forest (boxtree, hazelnut, rhododendron), in a deciduous forest (lime, beech, hornbeam, hazelnut), and in an old primary beech forest (MEYBOHM pers. comm., 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 15-25: Geostiba largata nov.sp.: (15) male habitus; (16) male forebody; (17) male elytra; (18- 22) median lobe of aedeagus in lateral and in ventral view; (23-25) spermatheca. Scale bars: 15: 1.0 mm; 16: 0.5 mm; 17-25: 0.1 mm.