Homaeotarsus denticulatus, Assing, 2009

Assing, V., 2009, On the Western Palaearctic and Middle Asian species of Ochthephilum STEPHENS, with notes on Cryptobium koltzei EPPELSHEIM (Coleoptera: Staphylinidae: Paederinae: Cryptobiina), Linzer biologische Beiträge 41 (1), pp. 397-426 : 422-424

Homaeotarsus denticulatus nov.sp. ( Figs 58-65 )

T y p e m a t e r i a l: Holotype 3: "3 / Nordwestl. / China / Chinkiang / Col. Reitter / koltzei / Emmerich Reitter vend III.1943 / ex coll. Scheerpeltz / Holotypus 3 Homaeotarsus sp.n., det. V. Assing 2008" (NHMW). Paratypes: 2♀♀: same data as holotype (NHMW, cAss).

D e s c r i p t i o n: Body length 8.0-9.0 mm. Habitus as in Fig. 58 . Coloration: Body uniformly blackish; legs dark yellowish; antennae dark-brown to brown, with the apical three antennnomeres yellowish-brown.

Head approximately 1.3 times as long as wide and shaped as in Fig. 59 ; punctation coarse and very dense, in median dorsal area (between eyes) less dense; interstices in median dorsal area without microsculpture; eyes approximately half as long as postocular region in dorsal view.

Pronotum approximately 1.2 times as long as wide, widest in the middle; lateral margins weakly concave or almost straight in dorsal view; punctation distinctly finer and somewhat less dense than that of head; interstices without microsculpture, on average slightly narrower than diameter of punctures; midline impunctate ( Fig. 59 ).

Elytra long, at suture approximately 0.95 times as long as pronotum; punctation slightly finer than that of pronotum and very dense (paratypes) to extremely dense and partly confluent (holotype) ( Fig. 59 ).

Abdomen approximately as wide as elytra or slightly narrower, widest at segments V-VI; punctation fine and dense; interstices with shallow microsculpture and somewhat glossy; posterior margin of tergite VII with palisade fringe.

3: sternite VII with almost truncate posterior margin ( Fig. 60 ); posterior incision of sternite VIII not very deep, broadly triangular ( Fig. 61 ); aedeagus small, 0.83 mm long, with small, but distinct tooth-like process at base of ventral process (best seen in lateral view) ( Figs 62-65 ).

E t y m o l o g y: The name (Latin, adjective) refers to the distinctive tooth at the base of the ventral process of the aedeagus.

C o m p a r a t i v e n o t e s: The genus Homaeotarsus is currently represented in the Palaearctic region by eleven species ( ASSING 2008a; SMETANA 2004). Based on the descriptions and available illustrations of the male primary and secondary sexual characters, H. denticulatus is characterised particularly by the shape of the aedeagus and the male sternite VII. In addition, it is distinguished from the geograpically closest Eastern Palaearctic congeners – H. humeralis (CAMERON 1924) , H. kumaonensis (CHAMPION 1921) , H. marginatus (MOTSCHULSKY 1858) , H. bernhaueri (CAMERON 1924) – by the uniformly blackish coloration of the forebody. In the similarly coloured H. rosti , the male sternite VII has a narrow and deep posterior incision. For illustrations of the male abdomen of the compared Eastern Palaearctic species and of the aedeagi of the Western Palaearctic species see CAMERON (1931) and COIFFAIT (1984), respectively.

In external morphology, the new species is practically indistinguishable from H. koltzei , with which it was confounded in the collection of the NHMW. Both species are, however, easily separated based on the shape of the male sternite VII ( H. koltzei : posterior margin distinctly concave in the middle), the shape of the male sternite VIII ( H. koltzei : posterior excision much deeper), and the completely different morphology of the aedeagus (see Figs 54-57 ).

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 material was collected in Xinjiang province, northwestern China. Additional data are not available.

Figures

Figs 54-65: Homaeotarsus koltzei (EPPELSHEIM) (54-57) and H. denticulatus nov.sp., holotype (58-65): (54, 60) male sternite VII; (55, 61) male sternite VIII; (56-57, 62-63) aedeagus in lateral and in ventral view; (58) habitus; (59) forebody; (64) base of ventral process of aedeagus in lateral view; (65) ventral process of aedeagus in ventral view. Scale bars: 58-59: 1.0 mm; 54-57, 60-63: 0.5 mm; 64-65: 0.1 mm.