Lathrobium ventricosum, Assing, 2013

Assing, Volker, 2013, On the Lathrobium fauna of China III. New species and additional records from various provinces (Coleoptera: Staphylinidae: Paederinae), Beiträge Zur Entomologie = Contributions to Entomology 63 (1), pp. 25-52 : 29-31

Lathrobium ventricosum sp. n.

( Figs 11-18 )

Type material:

Holotype : “ CHINA Sichuan, Gongga Shan, Hailuogou, above Camp 3, 3050 m 6. VII.96, 29°35N, 102°00E, C52 / collected by A. Smetana, J. Farkač and P. Kabátek / Holotypus  Lathrobium ventricosum sp. n., det. V. Assing 2012” (cSme) . Paratypes: 7 , 6 : same data as holotype (cSme, cAss, cSch); 1 : “ CHINA Sichuan, Gongga Shan, Hailuogou, above Camp 3, 3200 m 7. VII.96, 29°35N, 102°00E, C54 / collected by A. Smetana, J. Farkač and P. Kabátek ” (cSme); 2 , 1 : “ CHINA Sichuan, Gongga Shan, Hailuogou, above Camp 3, 3100 m 8. VII.96, 29°35N, 102°00E, C56 / collected by A. Smetana, J. Farkač and P. Kabátek ” (cSme, cAss); 6 , 3: “ CHINA, Sichuan, Gongga Shan, above Camp 3, 3050 m, 22.VII.1994, A. Smetana [C18]” (cSme, cAss); 5 , 4 : “ CHINA, Sichuan, Gongga Shan, abv. Camp 3, 3300-3350 m, 23.VII.1994, A. Smetana [C19]” (cSme, cAss); 4 : “ CHINA: Sichuan Gongga Shan, Hailuogou, Lake above Camp 2, 2750 m, 29°35N, 102°00E, 4.VII.1998, A. Smetana [C74] / 1998 China Expedition, J. Farkač, D. Král, J. Schneider & A. Smetana ” (cSme, cAss); 1 : “ CHINA: Sichuan Gongga Shan, Hailuogou, in front of Glacier 1, 2850 m, 29°35N, 102°00E, 7.VII.1998, A. Smetana [C75] / 1998 China Expedition, J. Farkač, D. Král, J. Schneider & A. Smetana ” (cSme) .

Etymology:

The specific epithet (Latin, adjective: fat, adipose) alludes to the short and large abdomen.

Description:

Species of short and stout habitus ( Fig. 11 ) and of relatively small size, with moderate sexual size dimorphism. Body length 5.8-7.0 mm (), 5.2-6.2 mm (); length of forebody 2.9-3.3 mm (), 2.7-3.0 mm (). Coloration: body dark reddish-brown to blackish-brown; legs reddish to reddish-brown; antennae reddish.

Head ( Fig. 12 ) approximately 1.05 times as long as broad, distinctly dilated posteriorly; punctation moderately coarse and rather sparse, even slightly sparser in median dorsal portion; interstices glossy, with very shallow, partly almost obsolete microreticulation. Eyes weakly convex and relatively large, approximately one third the length of postocular region in dorsal view and composed of approximately 40-50 ommatidia. Antenna 1.5-1.7 mm long.

Pronotum ( Fig. 12 ) rather short, approximately 1.2 times as long as broad and about 1.05-1.10 times as broad as head; punctation similar to that of head, but slightly denser; impunctate midline moderately broad; interstices without microsculpture.

Elytra ( Fig. 12 ) short, 0.52-0.55 times as long as pronotum; punctation somewhat variable, usually moderately dense, shallow, and weakly defined. Hind wings completely reduced. Protarsi with moderately pronounced sexual dimorphism.

Abdomen large and short, distinctly dilated from segments III to VI, widest at segments V/VI, approximately 1.15 times as broad as elytra; punctation fine and moderately dense, only slightly sparser on tergite VII than on anterior tergites; microsculpture fine and shallow, interstices rather glossy; posterior margin of tergite VII without palisade fringe; tergite VIII without sexual dimorphism, posterior margin weakly convex in both sexes.

: protarsomeres I-IV strongly dilated; sternites III-VI unmodified; sternite VII ( Fig. 13 ) transverse, approximately twice as broad as long, with extensive median impression, this impression with numerous moderately modified, short dark setae on either side of middle, posterior margin broadly and weakly concave, more distinctly concave in the middle; sternite VIII ( Fig. 14 ) distinctly transverse and with shallowly concave posterior excision, pubescence unmodified; aedeagus ( Figs 15-16 ) 1.4-1.5 mm long, symmetric; ventral process straight, not distinctly separated from aedeagal capsule; dorsal plate short, weakly sclerotized, and apically with acute and slender process; internal sac without sclerotized structures.

: protarsomeres I-VI distinctly dilated, but less so than in male; sternite VIII ( Fig. 17 ) approximately 1.0 mm long, approximately as long as broad; middle of posterior margin more or less truncate; tergite IX completely separated in the middle and with short postero-lateral processes; tergite X flat, reaching anterior margin of tergite IX ( Fig. 18 ).

Comparative notes:

This highly distinctive species differs from all other geographically close congeners by numerous external and sexual characters, particularly the habitus with a relatively short and stout abdomen, the moderately pronounced sexual size dimorphism, the shallow microsculpture of the head, the shape and chaetotaxy of the male sternites VII and VIII (especially the strongly transverse male sternite VII), the morphology of the aedeagus (ventral process fused with aedeagal capsule; dorsal plate of distinctive shape), and the female terminalia (short sternite VIII; completely divided tergite IX). Shared derived characters suggesting closer phylogenetic affiliations with other described species recorded from China were not found.

Distribution and natural history:

Lathrobium ventricosum is most likely endemic to the Gongga Shan, where it is apparently confined to higher elevations. The specimens were sifted in several localities at altitudes of 2750-3350 m.

Figures

Figs 11-18: Lathrobium ventricosum sp. n.: habitus (11); forebody (12); male sternite VII (13); male sternite VIII (14); aedeagus in lateral and in ventral view (15-16); female sternite VIII (17); female tergites IX-X (18). Scale bars: 11-12: 1.0 mm; 13-18: 0.5 mm.