Atheta (Microdota) bicoloricornis, Assing, 2009

Assing, V., 2009, New species and additional records of Homalotini, Athetini, Pygostenini, and Lomechusini from Yunnan, China (Coleoptera: Staphylinidae: Aleocharinae), Linzer biologische Beiträge 41 (1), pp. 485-507 : 492-494

Atheta (Microdota) bicoloricornis nov.sp. ( Figs 15-23 )

Holotype Ƌ: China: Yunnan [ CH 07-27], Nujiang Lisu Aut. Pref., Gaoligong Shan, creek valley 20 km NW Liuku, 25°58'49"N, 98°41'48"E, 3000 m, bamboo, shrubs, litter sifted, 9. VI.2007, M. Schülke / Holotypus Ƌ Atheta bicoloricornis sp.n. det. V. Assing 2007 (cAss).

D e s c r i p t i o n: 2.2 mm. Habitus as in Fig. 15 . Coloration: body pale reddish, with the head slighly darker; legs yellowish; antennae bicoloured, with the basal 3 antennomeres yellowish, sharply contrasting with the dark brown apical portion (antennomeres IV-XI).

Head of subcircular shape, 1.05 times as long as wide ( Fig. 16 ); punctation extremely fine, barely noticeable; surface with distinct microreticulation and almost matt. Eyes small ( Fig. 17 ), not projecting from lateral contours of head, approximately 1/4 the length of postocular region in dorsal view. Antennae gradually and distinctly incrassate apically, antennomere X more than twice as wide as long ( Fig. 18 ).

Pronotum approximately 1.15 times as wide as long and 1.15 times as wide as head; maximal width in anterior half; posterior angles weakly marked, rounded ( Fig. 16 ); punctation and microreticulation similar to those of head; pubescence of midline unclear (somewhat disturbed in the holotype).

Elytra short, at suture approximately 0.6 times as long as pronotum ( Fig. 16 ); punctation dense and fine, much more distinct than that of head and pronotum; microsculpture indistinct, interstices shiny. Hind wings completely reduced. Metatarsomere I short, very slightly longer than II.

Abdomen slightly wider than elytra, widest at segment V; tergites III-V anteriorly with shallow impression; punctation very fine, moderately dense on tergite III, decreasing in density from tergites IV-VI, and very sparse on tergite VII; microsculpture very shallow on anterior tergites, distinct on posterior tergites; posterior margin of tergite VII with very narrow, barely noticeable rudiment of a palisade fringe.

Ƌ: posterior margin of tergite VIII distinctly truncate in the middle ( Fig. 19 ); sternite VIII somewhat longer than tergite VIII, its posterior margin strongly convex ( Fig. 20 ); median lobe of aedeagus relatively small, 0.29 mm long ( Figs 21-22 ); apical lobe of paramere as in Fig. 23 .

♀: unknown. E t y m o l o g y: The name refers to the conspicuous coloration of the antennae, the dark coloration of the apical part distinctly contrasting with that of the remainder of the body.

C o m p a r a t i v e n o t e s: Previously, only eight micropterous Microdota species were known from China, six from northern Yunnan and two from Shaanxi ( ASSING 2002, 2004a, 2006; PACE 1999a); only one of them is of similarly pale coloration: A. geostiboides ASSING from northern Yunnan. From this species, A. bicoloricornis is distinguished by the distinctly bicolored and more strongly incrassate antennae with much more transverse preapical antennomeres, the paler abdomen (in A. geostiboides distinctly darker than the pronotum and the elytra), the less transverse pronotum, the absence of distinct microsculpture on the elytra, the different shape of the male sternite VIII (in A. geostiboides strongly elongated), the different morphology of the median lobe of the aedeagus, and by the completely different shape of the apical lobe of the paramere. For figures illustrating the external and sexual characters of A. geostiboides see ASSING (2004a); for illustrations of the other micropterous Microdota species known from China see ASSING (2002, 2006a) and PACE (1999a).

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 Gaoligong Shan, to the northwest of Liuku in western Yunnan province. As can be inferred from the adaptive reductions of pigmentation, eye size, and wings, as well as from the altitude (3000 m) of the type locality, the distribution of the species is probably restricted. The holotype was sifted from litter beneath bamboo and shrubs.

Figures

Figs 15-23: Atheta bicoloricornis nov.sp.: (15) habitus; (16) forebody; (17) head in lateral view; (18) antenna; (19) male tergite VIII; (20) male sternite VIII; (21-22) median lobe of aedeagus in lateral and in ventral view; (23) apical portion of paramere. Scale bars: 15: 1.0 mm; 16: 0.5 mm; 17-20: 0.2 mm; 21-22: 0.1 mm; 23: 0.05 mm.