Lathrobium bihastatum, 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 : 33-35

Lathrobium bihastatum sp. n.

( Figs 36-43 )

Type material:

Holotype : “ CHINA: W-Sichuan, Ya’an Pref., Fulin Co., Daxiang Ling , Pass N / Hanyuanjie 51 km NNE Shimian, smal [sic] stream, 29.39N, 102.37E, 2300 m, 10.VII.1999, leg. A. Pütz / Holotypus  Lathrobium bihastatum sp. n., det. V. Assing 2012” (cAss) . Paratypes: 2 : same date as holotype (cPüt); 1 : “ CHINA W. Sichuan (Ya‘an Pref., Fulin Co.) Daxiang Ling, road Hanyuanjie-Sipin , 51 km NNE Shimian, 2300 m, 29°39N 102°37E (river bank) 10.VII.1999 D. W. Wrase ” (cSch) .

Etymology:

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

Description:

Species of moderate size. Body length 8.0 mm (), 7.5- 8.2 mm (); length of forebody 3.6 mm (), 3.2-3.4 mm (). Coloration: body brown to blackish; legs and antennae reddish.

Head ( Fig. 36 ) approximately as broad as long; punctation moderately coarse and moderately dense, sparser in median dorsal portion; interstices with distinct microreticulation. Eyes weakly convex, approximately one third the length of postocular region in dorsal view, and composed of approximately 40-50 ommatidia. Antenna 1.8- 2.0 mm long.

Pronotum ( Fig. 36 ) moderately slender, approximately 1.25 times as long as broad and 1.05-1.10 times as broad as head; punctation similar to that of head; impunctate midline moderately broad; interstices without microsculpture.

Elytra ( Fig. 36 ) short, approximately 0.55 times as long as pronotum; punctation fine, shallow, and rather weakly defined. Hind wings completely reduced. Protarsi with pronounced sexual dimorphism.

Abdomen with moderately fine and very dense punctation, that of tergite VII noticeably sparser than that of anterior tergites; interstices with fine microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII with weakly pronounced sexual dimorphism.

: protarsomeres I-IV strongly dilated; tergite VIII with weakly convex posterior margin; sternites III-VI unmodified; sternite VII ( Fig. 37 ) moderately transverse, symmetric, and with median impression of triangular shape posteriorly, this impression with cluster of distinctly modified, short and stout black setae, posterior margin weakly concave in the middle; sternite VIII ( Fig. 38 ) noticeably transverse, symmetric, and with shallow median impression, on either side of middle with cluster of weakly modified dark setae posteriorly, posterior excision small and of semi-circular shape; aedeagus ( Figs 39-41 ) approximately 1.2 mm long, symmetric, and with ventral process of distinctive shape, apical portion of dorsal plate lamellate and moderately sclerotized, basal portion of dorsal plate short, internal sac with pair of distinctly sclerotized long spines.

: protarsomeres I-IV moderately dilated, much less so than in male; posterior margin of tergite VIII weakly and obtusely pointed in the middle; sternite VIII ( Fig. 42 ) approximately 1 mm long, moderately oblong, and convexly produced posteriorly; tergite IX with median portion undivided and moderately short, posterior processes moderately long and slender; tergite X much longer than tergite IX in the middle ( Fig. 43 ).

Comparative notes:

Based on the male and female sexual characters, particularly the presence of a pair of sclerotized spines in the internal sac of the aedeagus, L. bihastatum undoubtedly belongs to the L. bibaculatum group. The similarly derived morphology of the aedeagus (somewhat spearshaped ventral process, rather massive internal spines), as well as the similar modifications of the male sternites VII and VIII suggest that it is the adelphotaxon of L. erlangense PENG & LI , in press from the Erlang Shan, from which it is distinguished by larger body size, the stouter ventral process of the aedeagus, and by the posteriorly more broadly produced female sternite VIII.

Distribution and natural history:

The type locality is situated to the north-northeast of Shimian (western Sichuan) in the Daxiang Ling, where

the species is probably endemic. The specimens were collected on a stream bank at an altitude of 2300 m.

Figures

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.