Neosclerus concavus, Assing, 2017

Assing, Volker, 2017, A revision of Neosclerus CAMERON VI. Three new species from India, Thailand, and Vietnam (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 49 (1), pp. 317-325 : 320-322

Neosclerus concavus nov.sp. ( Figs 10-17 )

T y p e m a t e r i a l: Holotype Ƌ: " THAILAND [43] - Doi Pha Hom Pok, Tad Luang waterf., 19°52'N, 99°07'E, 1100 m, 27.I.29014, leg. Ob / Holotypus Ƌ Neosclerus concavus sp.n. det. V. Assing 2015 " (cAss). Paratype ♀: same data as holotype (cAss).

E t y m o l o g y: The specific epithet (Latin, adjective: concave, excavate) alludes to the pronounced posterior excision of the male sternite VII.

D e s c r i p t i o n: Body length 3.2-3.5 mm; length of forebody 1.8-2.0 mm. Coloration: head and pronotum blackish-brown to blackish; elytra pale-brown; abdomen brown to dark-brown; legs and antennae yellowish.

Head ( Fig. 10 ) 1.31-1.33 times as broad as long; punctation of dorsal surface coarse, umbilicate, and very dense, only slightly less dense posteriorly; interstices in median and anterior dorsal portion without, near posterior constriction with shallow microreticulation. Eyes very large and bulging, separated from posterior margin of head by less than the width of antennomere II.

Pronotum ( Fig. 10 ) approximately 1.05 times as broad as long and 0.82-0.86 times as broad as head; punctation similar to that of median portion of head, but less dense and not umbilicate; interstices without microsculpture and glossy; midline narrowly impunctate and with fine sulcus of variable length.

Elytra ( Fig. 10 ) 1.06-1.09 times as long as pronotum; punctation dense, distinctly finer than that of pronotum. Hind wings fully developed. Metatarsomere I approximately as long as the combined length of metatarsomeres II and III.

Abdomen narrower than elytra; punctation fine and moderately dense; interstices with shallow microreticulation; posterior margin of tergite VII with palisade fringe.

Ƌ: sternite VII ( Figs 11-13 ) moderately tranverse, posteriorly with a distinct dense cluster of modified short and stout black setae, posterior margin with a pronounced median excision of nearly semi-circular shape; sternite VIII ( Figs 14-15 ) weakly oblong, extensively without pubescence in median and postero-median portions, with few setae in antero-median portion and at the margins of the posterior excision, and with dense setae laterally, posterior excision V-shaped, its depth approximately one-fifth the length of sternite; aedeagus ( Figs 16-17 ) 0.58 mm long; ventral process straight, apically acute, and subapically with a pair of small teeth and a pair of indentures.

C o m p a r a t i v e n o t e s: Based on the male primary and secondary sexual characters, N. concavus belongs to the N. brevipennis group. Among the species of this group, it is characterized particularly by the pronounced posterior excision and the defined posterior cluster of dense modified setae of the male sternite VII, by the chaetotaxy of the male sternite VIII, and by the shapes of the ventral process and the internal structures of the aedeagus.

For illustrations of the male sexual characters of other species of the N. brevipennis group see ASSING (2011, 2013, 2015).

D i s t r i b u t i o n a n d b i o n o m i c s: The type locality is situated in the extreme north of Thailand, close to the border with Myanmar. The specimens were sifted from leaf litter near a stream at an altitude of 1100 m.

Figures

Figs 10-17: Neosclerus concavus nov.sp.: (10) forebody; (11) male sternite VII; (12-13) posteromedian portion of male sternite VII; (14) male sternite VIII in ventral view; (15) male sternite VIII in lateral view; (16-17) aedeagus in lateral and in ventral view. Scale bars: 10: 0.5 mm; 11, 14-17: 0.2 mm; 12-13: 0.1 mm.