Lathrobium diffissum, Assing, 2013

Assing, V., 2013, On the Lathrobium fauna of China IV. Six new species from Sichuan (Coleoptera: Staphylinidae: Paederinae), Linzer biologische Beiträge 45 (1), pp. 155-170 : 157-159

Lathrobium diffissum nov.sp.

( Figs 1-8 )

Type material: Holotype ♂: " China S Sichuan, S Xichang Mt. Luoji , 2300-2500 litter, 16.-24.07.96 Kurbatov / Holotypus ♂ Lathrobium diffissum sp.n. det. V. Assing 2013" ( MHNG) . Paratypes: 2♂♂, 2♀♀: same data as holotype ( MHNG, cAss).

Etymology: The specific epithet is the past participle of the Latin verb diffindere (to split) and alludes to the conspicuous fissure on the female tergite IX.

Description: Species of moderately large size and slender habitus; body length 7.8-9.0 mm; length of forebody 3.6-4.0 mm. Coloration: body dark-brown, with the elytra dark-reddish to reddish-brown; legs and antennae reddish.

Head ( Fig. 1 ) oblong, approximately 1.1 times as long as broad; punctation moderately coarse and moderately dense; interstices with fine microreticulation. Eyes small, 0.15- 0.20 times as long as postocular region in dorsal view, composed of approximately 40 small and weakly defined ommatidia. Antenna 1.9-2.2 mm long.

Pronotum ( Fig. 1 ) slender, approximately 1.35 times as long as broad, approximately as broad as, or slightly broader than head; punctation similar to that of head or slightly finer; impunctate midline rather narrow; interstices without microreticulation.

Elytra ( Fig. 1 ) rather slender, approximately 0.55 times as long and 1.05-1.10 times as broad as pronotum; punctation fine, shallow, and moderately dense. Hind wings completely reduced. Protarsi with pronounced sexual dimorphism.

Abdomen approximately 1.15 times as broad as elytra; punctation fine and dense on all tergites; interstices with very shallow microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII with distinct sexual dimorphism.

♂: tergite VIII with weakly convex posterior margin; sternites III-VI unmodified; sternite VII ( Fig. 3 ) moderately transverse, with shallow postero-median impression, pubescence very weakly modified, posterior margin concave in the middle; sternite VIII ( Fig. 2 ) weakly transverse, pubescence dense, but not distinctly modified, posterior margin weakly convex, without median excision; aedeagus ( Figs 4-6 ) approximately 1.3 mm long and symmetric; ventral process long, slender, strongly curved in lateral view, and apically acute, indistinctly spear-shaped; dorsal plate with lamellate, strongly sinuate (lateral view), and moderately long apical portion and with very short, lamellate and very weakly sclerotized basal portion; internal sac with pair of thin membranous structures and the usual ring-shaped structure.

♀: tergite VIII ( Fig. 7 ) distinctly, somewhat triangularly produced posteriorly; sternite VIII approximately 1.1 mm long, posterior margin produced and in the middle weakly concave; tergite IX ( Fig. 8 ) of distinctive morphology: antero-median portion long, with long fissure in the middle, but not completely divided, postero-lateral processes moderately long and slender; tergite X ( Fig. 8 ) weakly convex in cross-section anteriorly and flattened posteriorly, shorter than antero-median portion of tergite IX.

C o m p a r a t i v e n o t e s Lathrobium diffissum is evidently closely related to an undescribed manuscript species from Yele Hydropower Station in Shimian County, which will be described in the near future (PENG et al. in prep). Both species share an aedeagus of similar morphology (ventral process long, slender, curved, and apically indistinctly spear-shaped; basal portion of dorsal plate very short; internal sac without sclerotized structures), a similar shape of the male sternite VII (posterior margin concave in the middle, a male sternite VIII with dense, but not distinctly modified pubescence, and a long and undivided antero-median portion of the female sternite IX. Lathrobium diffissum is distinguished, however, by the shape of the male sternite VIII (transverse and without posterior excision), the shape of the aedeagus (ventral process more strongly curved; dorsal plate shorter and more strongly sinuate), by the less oblong, posteriorly less distinctly produced, and weakly concave female sternite VIII, and by the conspicuous fissure on the antero-median portion of the female tergite IX.

Distribution and natural history:The type locality is situated in the Luoji Shan [27°26'N, 102°24'E], some 50 km to the south-southeast of Xichang ( Map 1 ). The specimens were sifted at an altitude of 2300-2500 m.

Figures

Map 1: Geographic position of the Xiling Xue Shan (filled circle), the Luoji Shan (open triangle), and the type locality of L. formidabile nov.sp. (star) in China.

Figs 1-8: Lathrobium diffissum nov.sp.: (1) forebody; (2) male sternite VIII; (3) male sternite VII; (4-5) aedeagus in lateral and in ventral view; (6) apex of ventral process of aedeagus in lateral view; (7) female sternite VIII; (8) female tergites IX and X. Scale bars: 1: 1.0 mm; 2-5, 7-8: 0.5 mm; 6: 0.05 mm.