Geostiba (Sibiota) nigrohortensia, Assing, 2018

Assing, Volker, 2018, A revision of Geostiba of the West Palaearctic region. XXVI. New species and additional records, primarily from the Caucasus region (Coleoptera: Staphylinidae: Aleocharinae), Linzer biologische Beiträge 50 (2), pp. 1033-1054 : 1042-1043

Geostiba (Sibiota) nigrohortensia nov.sp. ( Figs 22-35 , 43 )

T y p e m a t e r i a l: Holotype ♂: "NAGORNO-KARABAKH [14] – WNW Stepanakert, 39°59'13''N, 46°14'45''E, 1610 m, mixed forest, 5.VII.2018, V. Assing / Holotypus ♂ Geostiba nigrohortensia sp. n. det. V. Assing 2018" (cAss) . Paratypes: 19♂♂, 46♀♀: same data as holotype (cAss, MNB) ; 16♂♂, 14♀♀: same data, but leg. Schülke ( MNB) ; 29♂♂, 34♀♀: "NAGORNO- KARABAKH – [19], pass 20 km SW Stepanakert , 39°41'50''N 46°39'00''E, 1730 m, 6.VII.2018, V. Assing" (cAss, MNB) ; 2♂♂, 3♀♀: same data, but leg. Schülke ( MNB) ; 1♂: "NAGORNO- KARABAKH – [22], pass 20 km SW Stepanakert, 39°42'13''N 46°39'02''E, 1700 m, 7.VII.2018, V. Assing " (cAss) .

E t y m o l o g y: The specific epithet (adjective: of the black garden) alludes to the currently known distribution, which is confined to Karabakh. This Azerbaijanian name means black garden.

D e s c r i p t i o n: Body length 2.3-2.8 mm. Habitus as in Fig. 22 . Coloration: body pale-reddish to reddish-brown with abdominal segment VI and the anterior half of segment VII more or less distinctly infuscate; legs yellow; antennae reddish-yellow. Eyes with pigmentation and composed of approximately five ommatidia. External characters as in G. tigrani ASSING, 2017 ( Armenia), distinguished only by the primary and secondary sexual characters.

Large ♂: elytra ( Figs 23-24 ) as in G. tigrani, with narrow and distinctly elevated sutural carina, this carina somewhat wider in anterior portion; tergite VII ( Fig. 25 ) with a pair of pronounced and posteriorly noticeably converging oblong tubercles; median lobe of aedeagus 0.24-0.25 mm long and shaped as in Figs 26-30 .

♀: spermatheca as in Figs 31-35.

I n t r a s p e c i f i c v a r i a t i o n: The male secondary sexual characters are more or less reduced in smaller males.

C o m p a r a t i v e n o t e s: Using the key to the Armenian Geostiba species in ASSING (2017a), G. nigrohortensia would key out at couplet 10, together with G. tigrani and G. pambakica ASSING, 2016, both of which are distributed in North Armenia. The new species is distinguished from them only by the sexual characters:

from G. tigrani by on average more pronounced and posteriorly more distinctly converging tubercles on the male tergite VII, by a relatively shorter ventral process of the aedeagus, by the shape of the crista apicalis, and by the shape of the spermatheca;

from G. pambakica by more pronounced and always distinctly separated tubercles on the male tergite VII (often fused or indistinctly separated in G. pambakica), by an apically less acute ventral process of the aedeagus (ventral view), the slightly different shape of the crista apicalis, and a much longer proximal portion of the spermatheca. For illustrations of G. tigrani and G. pambakica see ASSING (2016b: figures 42-52) and ASSING (2017a: figures 1-13, 22-38).

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 known distribution is confined to three localities in Nagorno-Karabakh, one in the north (48 km WNW Stepanakert) and two in a pass some 17 km to the southwest of Stepanakert. The specimens were sifted from moist litter and debris in mixed deciduous forests and near a stream at altitudes of 1610-1730 m. In the type locality ( Fig. 43 ), it was found together with G. unicuneata .

Figures

Figs 22-35: Geostiba nigrohortensia nov.sp.: (22) male habitus; (23) male forebody in dorsal view; (24) male forebody in lateral view; (25) male abdomen; (26-30) median lobe of aedeagus in lateral and in ventral view; (31-35) spermatheca. Scale bars: 22: 1.0 mm; 23-25: 0.5 mm; 26-35: 0.1 mm.

Figs 43-44: Type localities of Geostiba nigrohortensia nov.sp. (above) and G. deliqua nov.sp. (below).