Geostiba (Sipalotricha) marmotae, 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 : 1047-1049

Geostiba (Sipalotricha) marmotae nov.sp. ( Figs 45-51 )

T y p e m a t e r i a l: Holotype ♂: " UKRAINE - Kherson obl., Askania-Nova, Yuzhnyi , marmot burrows, 29.II.2017, leg. Gontarenko / Holotypus ♂ Geostiba marmotae sp. n. det. V. Assing 2018" (cAss) . Paratypes: 5♂♂, 3♀♀: same data as holotype (cGon, cAss) ; 2♀♀, same data, but 24.III.2017 (cGon, cAss) .

E t y m o l o g y: The specific epithet is the genitive of the Latin noun marmota (marmot) and alludes to the fact that all the type specimens were collected from marmot burrows.

D e s c r i p t i o n: Body length 2.0- 2.3 mm; length of forebody 0.8-0.9 mm. Coloration: forebody reddish-yellow to pale reddish-brown, with the head sometimes darker brown; abdomen blackish with segment VIII-X yellowish and the anterior segments more or less extensively reddish-yellow to pale brown; legs and antennae yellowish.

Head approximately as long as broad or weakly transverse, slightly wedge-shaped; punctation extremely fine, visible only at high magnification; interstices with or without shallow traces of microsculpture, glossy. Eyes small, composed of approximately 20

ommatidia. Antennae distinctly incrassate; antennomeres IV-X approximately twice as broad as long.

Pronotum approximately 1.2 times as broad as long and 1.1 times as broad as head, small in relation to the head; punctation extremely fine; microsculpture very shallow, but slightly more distinct than that of head; interstices glossy.

Elytra approximately 0.6 times as long as pronotum; punctation sexually dimorphic; interstices with shallow microreticulation. Hind wings completely reduced.

Abdomen slightly broader than elytra; punctation fine, moderately dense on anterior tergites, very sparse on posterior tergites; interstices with shallow, but distinct microreticulation; posterior margin of tergite VII without palisade fringe; posterior margin of tergite VIII sexually dimorphic.

♂: elytra ( Fig. 45 ) with strongly granulose punctation; posterior margin of tergite VIII somewhat produced and concave in the middle ( Figs 46-47 ); posterior margin of sternite VIII moderately strongly convex ( Fig. 48 ); median lobe of aedeagus ( Figs 49-50 ) approximately 0.25 mm long; ventral process straight and rather stout in lateral view; crista apicalis weakly convex and without distinct membrane in lateral view.

♀: elytra with simple, fine punctation; posterior margin of tergite VIII not produced in the middle, simply convex; posterior margin of sternite VIII broadly convex; spermatheca as in Fig. 51.

C o m p a r a t i v e n o t e s: Regarding the primary sexual characters, G. marmotae is similar to the geographically close G. cuneiceps (KRAATZ, 1856) ( Slovakia, Hungary). It is distinguished from this species by a more slender body, a more glossy forebody with less pronounced microsculpture, a pronounced dimorphism of the elytral punctation, on average darker coloration, a smaller aedeagus (G. cuneicormis: median lobe at least approximately 0.3 mm long) with a stouter (lateral view) and apically more acute (ventral view) ventral process, and by a spermatheca of slightly different shape. From G. gontarenkoi ASSING, 2005 ( Ukraine: region to the north of Odessa), its geographically closest consubgener, G. marmotae is distinguished by on average less pronounced microsculpture of the forebody, more extensively and more distinctly granulose punctation of the male elytra, the shape of the male tergite VIII (G. gontarenkoi: male tergite VIII more transverse and with smoothly convex posterior margin), the shape of the aedeagus (G. gontarenkoi: ventral process smoothly curved in lateral view and less strongly tapering in ventral view; crista apicalis and crista proximalis more pronounced), and by the shape of the spermatheca (G. gontarenkoi: distal portion not distinctly dilated apically; proximal portion shorter, less slender, and proximally less strongly dilated. For illustrations of G. cuneiformis and G. gontarenkoi see ASSING (2005).

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: Thetypelocalityissituated in South Ukraine, to the north of the Krym peninsula. Remarkably, all eleven type specimens were collected from burrows of the steppe marmot (Marmota bobak (MÜLLER, 1776)). An association of Geostiba species with mammal nests, however, has never been observed, so that it is uncertain if marmot burrows are the true habitat of G. marmotae or if these records are merely accidental.

Figures

Figs 45-51: Geostiba marmotae nov.sp.: (45) sutural portion of male elytra; (46) apex of male abdomen; (47) male tergite VIII; (48) male sternite VIII; (49-50) median lobe of aedeagus in lateral and in ventral view; (51) spermatheca. Scale bars: 46-48: 0.2 mm; 45, 49-51: 0.1 mm.