Lathrobium hamulatum, Assing, 2013

Assing, V., 2013, On the Lathrobium fauna of China IV. Six new species from Sichuan (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 45 (1), pp. 155-170 : 159-161

Lathrobium hamulatum nov.sp.

( Figs 9-16 )

Type material: Holotype ♂: " China S Sichuan, S Xichang Mt. Luoji , 2300-2500 litter, 16.-24.07.96 Kurbatov / Holotypus ♂ Lathrobium hamulatum sp.n. det. V. Assing 2013" ( MHNG) . Paratypes: 1♂, 1♀: same data as holotype ( MHNG, cAss).

Etymology: The specific epithet is an adjective derived from the diminutive of the Latin noun hamus (hook) and alludes to the hook-shaped apex of the ventral process of the aedeagus.

Description: Species of moderate size; body length 6.0-7.0 mm; length of forebody 2.9-3.2 mm. Habitus as in Fig. 9 . Coloration: body dark-brown; legs and antennae reddish.

Head ( Fig. 10 ) oblong, approximately 1.05 times as long as broad; punctation moderately coarse and moderately dense; interstices with fine, but distinct microreticulation. Eyes small, approximately one fourth as long as postocular region in dorsal view, composed of approximately 25 moderately small and defined ommatidia. Antenna approximately 1.6 mm long.

Pronotum ( Fig. 10 ) slender, 1.30-1.35 times as long as broad, approximately 1.05 times as broad as head; punctation similar to that of head; impunctate midline moderately broad; interstices without microreticulation.

Elytra ( Fig. 10 ) short, approximately half as long as pronotum; punctation fine, shallow, and moderately dense. Hind wings completely reduced. Protarsi with moderately pronounced sexual dimorphism.

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

♂: tergite VIII with weakly convex posterior margin; sternites III-VI unmodified; sternite VII ( Fig. 11 ) moderately transverse, with shallow and rather small postero-median impression of triangular shape, middle of this impression without setae, peripheral region with moderately modified black setae, posterior margin concave in the middle; sternite VIII ( Fig. 12 ) indistinctly oblong, in the middle narrowly without setae, on either side of middle with moderately modified pubescence increasing in density posteriad, posterior excision V-shaped, small, but distinct, posterior margin produced on either side of posterior excision; aedeagus ( Figs 13-14 ) 1.1 mm long and symmetric; ventral process basally almost straight and apically of distinctive shape in lateral view; dorsal plate with very long and lamellate apical portion, and with short basal portion; internal sac without sclerotized structures.

♀: posterior margin of tergite VIII obtusely angled in the middle; sternite VIII ( Fig. 15 ) 1.0 mm long, distinctly oblong, posteriorly distinctly, convexly produced; tergite IX ( Fig. 16 ) with moderately long and undivided antero-median portion, and with moderately long and slender postero-lateral processes; tergite X ( Fig. 16 ) weakly convex in cross-section, approximately twice as long as antero-median portion of tergite IX.

Comparative notes Lathrobium hamulatum is characterized particularly by the distinctive shape of the aedeagus and additionally by the shape and chaetotaxy of the male sternite VIII, as well as by the shapes of the female sternite VIII and tergites IX-X. Based on the sexual characters, closer affiliations with other Lathrobium species are not evident. Aside from the sexual characters, it differs from the sympatric L. diffissum by smaller body size, less slender habitus, the fewer and larger ommatidia of the eyes, and the sparser punctation of the abdominal tergites VII and VIII, and from the similarly sympatric L. bivirgatum by larger body size, darker coloration, and a more slender pronotum.

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 The type locality and other data are identical to those of L. diffissum .

Figures

Figs 9-16: Lathrobium hamulatum nov.sp.: (9) habitus; (10) forebody; (11) male sternite VII; (12) male sternite VIII; (13-14) aedeagus in lateral and in ventral view; (15) female sternite VIII; (16) female tergites IX and X. Scale bars: 9-10: 1.0 mm; 11-16: 0.5 mm.