Lathrobium constrictum, Assing, 2014

Assing, Volker, 2014, New species and records of Lathrobium from the Palaearctic region, primarily from Nepal (Coleoptera: Staphylinidae: Paederinae), Beiträge Zur Entomologie = Contributions to Entomology 64 (1), pp. 1-28 : 5-6

Lathrobium constrictum sp. n.

( Figs 10–15 , Map 1 )

Type material: Holotype  [dissected prior to present study]: “ NEPAL 3000 m. Kali Danda Massif, V.1989 P. Morvan / L. alticola Coiff.?, det. 198 [sic], G. de Rougemont / Holotypus  Lathrobium constrictum sp. n., det. V. Assing 2013” (cRou).

Etymology: The specific epithet (Latin, adjective) alludes to the subapically distinctly constricted ventral process of the aedeagus.

Description: Slender species; body length 7.8 mm; length of forebody 3.7 mm. Habitus as in Fig. 10 . Coloration: head and pronotum reddish; elytra reddish-brown; abdomen dark-brown; legs and antennae reddish.

Head ( Fig. 11 ) 1.08 times as long as broad; punctation sparse and moderately coarse; interstices much broader than diameter of punctures, with fine and distinct microreticulation. Eyes moderately small, composed of approximately 30 ommatidia, approximately one-fourth as long as postocular region in dorsal view. Antenna 2.2 mm long.

Pronotum ( Fig. 11 ) slender, 1.33 times as long as broad and 0.97 times as broad as head; punctation similar to that of head; midline broadly impunctate; interstices without microsculpture.

Elytra ( Fig. 11 ) 0.57 times as long as pronotum; punctation fine and shallow; interstices without distinct microsculpture; suture gaping posteriorly. Hind wings completely reduced.

Abdomen approximately 1.15 times as broad as elytra; punctation fine and moderately dense; interstices with fine transverse microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII with weakly convex posterior margin.

: protarsomeres I–IV moderately dilated; sternite VII ( Fig. 12 ) moderately transverse, with relatively sparse unmodified pubescence, posterior margin broadly concave; sternite VIII ( Fig. 13 ) weakly transverse, with unmodified pubescence, posterior excision very broadly V-shaped; aedeagus ( Figs 14–15 ) approximately 1.1 mm long, slender, and symmetric; ventral process nearly straight in lateral view and conspicuously constricted subapically in ventral view; dorsal plate reduced, not sclerotized; internal sac with long membranous structure.

: unknown.

Comparative notes: As can be inferred from the external (slender habitus) and the male sexual characters (sternite VIII with unmodified pubescence and with broad and shallow posterior excision; aedeagus slender, symmetric, without sclerotized dorsal plate, and with long membranous structure in internal sac), L. constrictum belongs to the L. discissum group. This group previously included two species from Darjeeling ( India: West Bengal) and the extreme east of Nepal: L. discissum ASSING, 2012 and L. separatum ASSING, 2012 . From both species, L. constrictum differs by the conspicuous shape of the ventral process of the aedeagus (ventral view). It is additionally distinguished from L. discissum by the less transverse sternite VII with sparser pubescence and a differently shaped posterior margin, as well as by the more sparsely pubescent male sternite VIII, and from L. separatum by distinctly larger body size ( L. separatum : length of forebody 2.7–3.0 mm). For illustrations of the previously described species of the L. discissum group see ASSING (2012).

Distribution and natural history: The type locality is situated in the Kali Danda ( Map 1 ), a mountain range to the west of the Singalila range and to the south of the Kangchenjunga Himal in Taplejung District (ca. 25 km E Taplejung; approximately 27°22.5'N, 87°55–58'E). The holotype was collected at an altitude of 3000 m.

Figures

Map 1: Distributions of Lathrobium species in Nepal: L. semicirculatum (white triangles), L. constrictum (black triangle), L. descendens (white circles), L. ascendens (black circle), L. rude (white star), L. latibasale (black star), L. eques (white diamond), L. equitans (black diamond), L. abruptum (black square), L. kemum (white square).

Figs 1–15: Lathrobium semicirculatum sp. n. (1–9) and L. constrictum sp. n. (10–15): habitus (1, 10); forebody (2, 11); male sternite VII (3, 12); male sternite VIII (4, 13); aedeagus in lateral and in ventral view (5–6, 14–15); apical portion of aedeagus in ventral view (7); female sternite VIII (8); female tergites IX–X (9). Scale bars: 1–2, 10–11: 1.0 mm; 3–9, 12–15: 0.5 mm.