Lathrobium bivirgatum nov.sp. (Figs 17-21)

Type material: Holotype ♂: " China S Sichuan, S Xichang Mt. Luoji, 2300-2500 litter, 16.-24.07.96 Kurbatov / Holotypus ♂ Lathrobium bivirgatum sp.n. det. V. Assing 2013" (MHNG).

Etymology: The specific epithet is composed of the Latin prefix bi- (two) and an adjective derived from the Latin noun virga (rod). It refers to the presence of a pair of long spines in the internal sac of the aedeagus.

Description: Small species; body length 6.2 mm; length of forebody 2.8 mm. Coloration: body reddish-brown; legs and antennae pale-reddish.

Head (Fig. 17) oblong, 1.09 times as long as broad; punctation moderately coarse and moderately dense; interstices with fine, but distinct microreticulation. Eyes small, approximately one fifth as long as postocular region in dorsal view, composed of approximately 20 moderately small and moderately defined ommatidia. Antenna 1.5 mm long.

Pronotum (Fig. 17) slender, 1.25 times as long as broad and approximately 1.05 times as broad as head; punctation similar to that of head; impunctate midline moderately broad; interstices without microreticulation.

Elytra (Fig. 17) 0.53 times as long as pronotum; punctation fine, shallow, and moderately dense. Hind wings completely reduced.

Abdomen approximately 1.1 times as broad as elytra; punctation fine and moderately dense on tergites III-VI, sparser on tergites VII and VIII; posterior margin of tergite VII without palisade fringe.

♂: protarsomeres I-IV strongly dilated; tergite VIII with weakly convex posterior margin; sternites III-VI unmodified; sternite VII (Fig. 18) moderately transverse, with shallow and rather extensive postero-median impression, this impression with distinctly modified stout black setae, posterior margin weakly concave; sternite VIII (Fig. 19) approximately as long as broad, in posterior median portion with dense and distinctly modified stout black setae, posterior excision very small and broadly V-shaped; aedeagus (Figs 20-21) 1.2 mm long and symmetric; ventral process long and very slender, subapically weakly bisinuate in lateral view and apically acute; dorsal plate with apical portion long, boat-shaped in cross-section, and apically acute in dorsal view, basal portion minute, very short and very thin both in lateral and in dorsal view; internal sac with pair of long, rather weakly sclerotized spines.

♀: unknown.

Comparative notes: Based on the similarly derived morphology of the aedeagus, particularly the presence of a pair of long spines in the internal sac, and on the shapes and chaetotaxy of the male sternites VII and VIII, Lathrobium bivirgatum belongs to the L. bibaculatum group, which was previously represented in Sichuan by five species from the Erlang Shan, the Daxiang Ling, and the Labahe Natural Reserve (ASSING in press b). From the sympatric L. diffissum and L. hamulatum, it is readily distinguished not only by the different male sexual characters, but also by smaller body size, paler coloration, a less slender pronotum, and the less numerous ommatidia of the eyes.

Distribution and natural history The type locality and other data are identical to those of L. diffissum and L. hamulatum .