Lathrobium coniunctum 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 : 53-54

Lathrobium coniunctum Assing & Peng sp. n. Figs 2B410

Type material.

Holotype ♂: 'CHINA: Sichuan Prov., Emeishan City, Mt. Emeishan, 29°33'N, 103°21'E, 21.vii.2012, alt. 1,700-1,900 m, Dai, Peng & Yin leg. / Holotypus ♂ Lathrobium coni unctum sp. n., det. Assing & Peng 2012'. Paratypes: 2♂♂: same label data as holotype; 2♀♀: same data, but ' 29°33'N, 103°20'E, 23.vii.2012, alt. 2,000-2,300 m' (SNUC); 1♂, 2♀♀: '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♀: 'P. R. CHINA, Sichuan, Emei Shan, 29°32.932'N, 103°20.466'E, 2310 m, 01.vii.2009, sifting 14, V. Grebennikov' (paratypes in SNUC, CAS, cSme, cAss).

Etymology.

The specific epithet (Latin, adjective: connected, fused) alludes to the merged ventral process and dorsal plate of the aedeagus and emphasizes the hypothesized close relationship of Lathrobium coniunctum to Lathrobium iunctum and the following species.

Description.

Body length 7.1-9.0 mm; length of forebody 3.4-3.8 mm. Habitus as in Fig. 2B. Legs reddish to reddish-brown. Other external characters as in Lathrobium iunctum .

Male. Sternites III-VI unmodified. Sternite VII distinctly transverse, with slightly asymmetric, somewhat oblique, and relatively extensive median impression, this impression with defined and extensive cluster of numerous distinctly modified, short and stout black setae; posterior margin bisinuate, with shallow excision in asymmetric position (Fig. 4D). Sternite VIII weakly transverse, with small and shallow, somewhat asymmetrically oblique median impression posteriorly, this impression with a cluster of distinctly modified, short and stout black setae on either side of middle; posterior excision shallow and in asymmetric position (Fig. 4E). Sternite IX as in Fig. 4G. Aedeagus (Figs 4F, H) approximately 1.4 mm long (from base of capsule to apex of dorsal plate), slender, distinctly asymmetric, and with small basal portion; ventral process and dorsal plate fused; dorsal plate apically obliquely bifid in ventral view; internal sac with small and weakly sclerotized basal sclerite.

Female. Sternite VIII approximately as long as broad and with distinctly convex posterior margin (Fig. 4B). Tergite IX undivided in the middle, with short median portion, and with long posterior processes; tergite X more than twice as long as tergite IX in the middle (Fig. 4C).

Comparative notes.

Lathrobium coniunctum is undoubtedly closely related to Lathrobium iunctum . This conclusion is supported by the similarly derived structure of the aedeagus (ventral process and dorsal plate fused, asymmetric, and slender; basal portion small; internal sac with small and weakly sclerotized basal sclerite); the similarly derived shape and chaetotaxy of the male sternite VII (median impression obliquely asymmetric and with defined, extensive cluster of distinctly modified setae), by the similar female secondary sexual characters (sternite VIII relatively short; tergite IX with short median portion and with long postero-lateral processes), as well as by the extremely similar external characters. Both species are best distinguished by the completely different shape and chaetotaxy of the male sternite VIII and by the differently shaped apex of the aedeagus.

Distribution and natural history.

Like Lathrobium iunctum , Lathrobium coniunctum is probably endemic to the Emei Shan, where the type specimens were sifted from leaf litter at elevations from approximately 1,700 to 2,310 m, partly together with Lathrobium iunctum . One of the collecting sites is illustrated in Fig. 10.