Lathrobium bispinigerum, 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 : 32-33

Lathrobium bispinigerum sp. n.

( Figs 26-31 , 33-35 )

Type material:

Holotype : “ CHINA: W-Sichuan 1999, Ganzi Tibet. Aut. Pref., Luding Co., W Erlangshan-Pass, 2600 m, 7 km SSE Luding, 29°51'N, 102°15'E, Laubstreu, Pilze, 29. VI., leg. M. Schülke / Holotypus  Lathrobium bispinigerum sp. n., det. V. Assing 2012” (cSch) . Paratypes: 4 , 6 : same data as holotype (cSch, cAss); 1 : “ CHINA: W-Sichuan 1999, Ya‘an Prefecture , Tianquan Co., E Erlangshan Pass, 2900 m, 9 km SE Luding, 29°52N, 102°18E, Gesiebe, 20. VI., leg. M. Schülke ” (cAss); 1 : “ CHINA: W-Sichuan, Ya‘an Prefecture, Tianquan Co., W Erlang Shan Pass / 2780 m, 21.VI.1999, 29.51.27N, 102.15.47E, leg. A. Pütz, sifted” (cPüt); 1 : same data, but 29.VI.1999 (cAss) .

Etymology:

The specific epithet (Latin, adjective: with two spines) refers to the presence of two sclerotized spines in the internal sac of the aedeagus.

Description:

Relatively small species, without evident sexual size dimorphism. Body length 6.2-7.0 mm; length of forebody 2.7-3.1 mm. Habitus as in Fig. 26 . Coloration: body darkbrown to blackish-brown, elytra often more or less extensively paler brown; legs reddish to pale reddish-brown; antennae reddish.

Head ( Fig. 27 ) as long as broad or weakly transverse, 1.00-1.04 times as broad as long; punctation moderately coarse and moderately dense, sparser in median dorsal portion; interstices with distinct microreticulation. Eyes weakly convex and moderately small, one fourth to nearly one third the length of postocular region in dorsal view and composed of approximately 40-50 ommatidia. Antenna approximately 1.7 mm long.

Pronotum ( Fig. 27 ) moderately slender, approximately 1.25 times as long as broad and about 1.05 times as broad as head; punctation similar to that of head; impunctate midline rather narrow to moderately broad; interstices without microsculpture.

Elytra ( Fig. 27 ) short, approximately 0.55 times as long as pronotum; punctation fine, sparse, shallow, and often weakly defined. Hind wings completely reduced. Protarsi with pronounced sexual dimorphism.

Abdomen with very fine, somewhat indistinct, and not particularly dense punctation, that of tergite VII distinctly sparser than that of anterior tergites; interstices with fine microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII without sexual dimorphism, with weakly convex posterior margin.

: protarsomeres I-IV strongly dilated; sternites III-VI unmodified; sternite VII ( Fig. 33 ) moderately transverse, symmetric, and with defined median impression of triangular shape posteriorly, this impression with cluster of numerous strongly modified, short and stout black setae, posterior margin distinctly concave in the middle; sternite VIII ( Fig. 34 ) weakly transverse, symmetric, and with long median impression, on either side of middle with numerous moderately modified black setae, posterior excision broad and not very deep; aedeagus ( Figs 28-30 ) approximately 1.1 mm long, almost symmetric, and with conspicuously long and straight ventral process, apical portion of dorsal plate thin, lamellate, and rather weakly sclerotized, basal portion of dorsal plate short and very thin, internal sac with pair of distinctly sclerotized, broad-based spines.

: protarsomeres I-IV moderately dilated, much less so than in male; sternite VIII ( Fig. 35 ) approximately 0.9 mm long, rather weakly oblong, and convexly produced posteriorly; tergite IX with median portion undivided and moderately short, posterior processes moderately long and slender; tergite X nearly twice as long as tergite IX in the middle ( Fig. 31 ).

Comparative notes:

Based on the similar external and sexual characters, particularly the presence of a pair of spines in the internal sac and the shape of the ventral process of the aedeagus, L. bispinigerum is the adelphotaxon of L. bibaculatum from the same mountain. It is distinguished from this species by slightly smaller body size, the more strongly modified male sternite VII (posteriorly with more numerous modified setae, posterior concavity more distinct), the more strongly modified male sternite VIII (pubescence distinctly modified posteriorly, posterior excision deeper), the straight and relatively longer ventral process of the aedeagus, the shorter, more broadbased, and more strongly sclerotized spines in the internal sac of the aedeagus, and the shorter female tergite X in relation to the median portion of tergite IX.

Distribution and natural history:

The species was discovered in three geographically close localities near the Erlang Shan Pass in western Sichuan, where the specimens were sifted at elevations of 2600- 2900 m.

Figures

Figs 19-31: Lathrobium bibaculatumsp. n. (19-25) and L. bispinigerum sp. n. (26-31): forebody (19, 27); male sternite VII (20); male sternite VIII (21); aedeagus in lateral and in ventral view (22-23, 28-29); internal structures of aedeagus in dorsal view (24, 30); female tergites IX-X (25, 31); habitus (26). Scale bars: 19, 26-27: 1.0 mm; 20-25, 28-31: 0.5 mm.

Figs 32-43: Lathrobium bibaculatum sp. n. (32), L. bispinigerum sp. n. (33-35), and L. bihastatum sp. n. (36-43): female sternite VIII (32, 35, 42); male sternite VII (33, 37); male sternite VIII (34, 38); forebody (36); aedeagus in lateral and in ventral view (39-40); internal structures of aedeagus in dorsal view (41); female tergites IX-X (43). Scale bars: 36: 1.0 mm; 32-35, 37-43: 0.5 mm.