Lathrobium hastatum Assing & Peng

Assing, Volker, Peng, Zhong & Zhao, Mei-Jun, 2013, On the Lathrobium fauna of the Emei Shan, Sichuan, China (Coleoptera, Staphylinidae, Paederinae), ZooKeys 277, pp. 47-67 : 58-60

Lathrobium hastatum Assing & Peng sp. n. Figs 2E79

Type material.

Holotype ♂: 'CHINA: Sichuan Prov., Emeishan City, Mt. Emeishan, 29°33'N, 103°20'E, 21.vii.2012, alt. 2,000-2,300 m, Dai, Peng & Yin leg. / Holotypus ♂ Lathrobium hastatum sp. n., det. Assing & Peng 2012' (SNUC). Paratypes: 6♂♂, 11♀♀: 'P. R. CHINA, Sichuan, Emei Shan, 29°33.6'N, 103°20.6'E, 27.vi.-5.vii.2009, 1800-2400 m, siftings 11-17, V. Grebennikov'; 1♂, 2♀♀: 'P. R. CHINA, Sichuan, EmeiShan, 29°32'56.0"N, 103°20'28.0"E, 2310 m, 20.vi.2010, sifting 38, V. Gre bennikov'; 4♀♀: 'P. R. CHINA, Sichuan, EmeiShan, 29°33'36.3"N, 103°20'38.0"E, 1947 m, 15.vi.2010, sifting 33, V. Grebennikov'; 1♀: 'CHINA Sichuan, Emei Shan, Leidongping, 2500 m, 18.VII.1996, 29°32N, 103°21E C65 / collected by A. Smetana, J. Farkač and P. Kabátek' (Paratypes in CAS, SNUC, cSme, and cAss).

Etymology.

The specific epithet (Latin, adjective: armed with a spear) alludes to the presence of a long spine in the internal sac of the aedeagus.

Description.

Species of relatively small and somewhat variable size, without sexual size dimorphism. Body length 6.3-7.6 mm; length of forebody 2.9-3.3 mm. Habitus as in Fig. 2E. Coloration: body brown to blackish-brown, abdominal apex indistinctly paler; legs and antennae reddish.

Head weakly oblong, approximately 1.05 times as long as broad; punctation variable, relatively fine to moderately coarse and moderately sparse to moderately dense, sparser in median dorsal portion; interstices with fine but distinct microreticulation. Eyes weakly convex and small, approximately one fourth as long as postocular region in dorsal view and composed of approximately 20 weakly defined ommatidia. Antenna 1.6-1.8 mm long.

Pronotum slender, approximately 1.35 times as long as broad and approximately 1.05 times as broad as head; punctation similar to that of head or somewhat finer; impunctate midline moderately broad; interstices without microsculpture.

Elytra short, weakly dilated posteriorly, little more than 0.50 times as long as pronotum; punctation somewhat variable, usually shallow and moderately defined. Hind wings completely reduced. Protarsi with weakly pronounced sexual dimorphism.

Abdomen with fine and rather dense punctation, that of tergite VII slightly sparser than that of anterior tergites; interstices with fine microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII without sexual dimorphism, with truncate to weakly concave posterior margin.

Male. Sternites III-VI unmodified. Sternite VII strongly transverse, symmetric, with shallow median impression posteriorly, this impression with sparse and weakly modified dark setae (Fig. 7D). Sternite VIII moderately transverse, symmetric, with pair of small impressions posteriorly, these impressions with numerous distinctly modified, stout and dark setae; posterior margin bisinuate, i.e., the shallow posterior excision with median projection (Fig. 7E). Sternite IX as in Fig. 7C. Aedeagus (Figs 7F, G) approximately 1.1 mm long; ventral process subapically strongly curved and apically acute in lateral view; apical portion of dorsal plate large, long, apically very acute, and distinctly sclerotized; basal portion of dorsal plate very short; internal sac with long and straight sclerotized spine and with additional lamellate apical structure.

Female. Sternite VIII 0.9-1.0 mm long, weakly oblong, of slightly variable shape; posterior margin distinctly produced, middle weakly to distinctly convex (Figs 7A, B). Tergite IX undivided in the middle, with long median portion, and with relatively short postero-lateral processes; tergite X much shorter than tergite IX in the middle.

Comparative notes.

The similarly derived shape and chaetotaxy of the male sternite VIII (posteriorly with pair of impressions, these impressions with modified setae; posterior excision with median projection), the similarly derived morphology of the aedeagus (apical portion of dorsal plate large, apically acute, and distinctly sclerotized; basal portion of dorsal plate very short; internal sac with long sclerotized spine and apically with additional sclerite), the similar shape of the female sternite VIII, and the similarly slender pronotum suggest that, among the described species recorded from the Emei Shan, Lathrobium hastatum is most closely related to Lathrobium ensigerum . It is at once distinguished from this species by much smaller body size and by the sexual characters.

Distribution and natural history.

Lathrobium hastatum is probably endemic to the Emei Shan. The specimens were sifted from leaf litter at elevations between 1,800 and 2,500 m, together with Lathrobium iunctum , Lathrobium coniunctum , and/or Lathrobium bisinuatum . The locality where the holotype was collected is illustrated in Fig. 9. The ovaries of one of the dissected females contained a mature egg.