Lathrobium ascendens, 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 : 8

Lathrobium ascendens sp. n.

( Figs 25–29 , 45 , 138–139 , Map 1 )

Type material: Holotype : “ NEPAL Karnali / Humla , 16 km W Simikot, 3 km NW Sankha-La 47–4800 m, 29°56'39"N, 81°39'02"E, 30.VI.2001 leg. A. Weigel / Holotypus  Lathrobium ascendens sp. n., det. V. Assing 2013” ( NME).

Paratype : same data as holotype (cAss).

Etymology: The specific epithet is the present participle of the Latin verb ascendere (to climb up). It alludes to the high altitude of the type locality.

Description: Body length 5.3–5.8 mm; length of forebody 3.1–3.3 mm. Body slender and somewhat flattened; habitus as in Fig. 25 . Coloration: body reddish, with the elytra reddish-yellow; legs dark-yellowish; antennae palereddish.

Head ( Fig. 26 ) 1.02–1.06 times as long as broad, weakly convex in cross-section; punctation dense and rather coarse; interstices on average narrower than diameter of punctures, with shallow microreticulation. Eyes reduced to minute subcircular rudiments without pigmentation and with approximately 10 ommatidia. Antenna long and slender, 2.1 mm long.

Pronotum ( Fig. 26 ) weakly convex in cross-section and conspicuously slender, 1.4 times as long as broad and 0.84 times as broad as head, widest anteriorly; lateral margins distinctly converging posteriorly and somewhat convex in dorsal view; punctation sparser and somewhat less coarse than that of head; midline rather narrowly impunctate; interstices without microsculpture.

Elytra ( Fig. 26 ) slender, 0.61–0.64 times as long as pronotum, combined width 1.28–1.36 times the length of suture; humeral angles nearly completely obsolete; suture gaping posteriorly; punctation very shallow and ill-defined; interstices without distinct microsculpture. Hind wings completely reduced. Protarsomeres I–IV with weakly pronounced sexual dimorphism.

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

: protarsomeres I–IV moderately dilated; sternite VII ( Fig. 138 ) strongly transverse and with unmodified pubescence, posterior margin broadly and weakly concave, in the middle weakly convex; sternite VIII ( Fig. 27 ) transverse, approximately 1.2 times as broad as long, posterior excision rather broad and not very deep, 0.15 times as deep as length of sternite; aedeagus ( Figs 28–29 ) 0.85 mm long; dorsal plate with very long, distinctly sclerotized, and apically hooked apical portion, and with short membranous basal portion; internal sac with a pair of long, moderately sclerotized, and apically acute structures.

: protarsomeres I–IV slightly less distinctly dilated than in male; sternite VIII ( Fig. 139 ) weakly transverse, 1.08 times as broad as long, posterior margin rather weakly convex and in the middle weakly concave; tergite IX ( Fig. 45 ) undivided in the middle, posterolateral processes apically acute and rather short, but distinctly extending beyond apex of tergite X; tergite X ( Fig. 45 ) distinctly convex in cross-section, of oval shape, and noticeably shorter than antero-median portion of tergite IX.

Comparative notes: As can be inferred from the highly similar external and sexual characters, L. ascendens is closely allied to L. descendens , from which it differs particularly by the coarse and denser punctation of the head, the larger and subcircular eye rudiments with more ommatidia, the slightly different shape of the pronotum, the slightly different chaetotaxy of the male sternite VIII, the less deep posterior excision of the male sternite VIII, the larger aedeagus with a differently shaped ventral process and with longer and more strongly sclerotized internal spines, and by the less slender and differently shaped female sternite VIII.

Distribution and natural history: The type locality is situated in Humla District, West Nepal ( Map 1 ), at an altitude of 4700–4800 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 16–29: Lathrobium descendens sp. n. (16–24) and L. ascendens sp. n. (25–29): habitus (16, 25); forebody (17, 26); male sternite VII (18); male sternite VIII (19, 27); aedeagus in lateral and in ventral view (20–22, 28–29); female sternite VIII (23); female tergites IX–X (24). Scale bars: 16–17, 25–26: 1.0 mm; 18–24, 27–29: 0.5 mm.

Figs 30–45: Lathrobium rude sp. n. (30–35), L. latibasale sp. n. (36–44) and L. ascendens sp. n. (45): habitus (30, 36); forebody (31, 37); male sternite VII (32, 38); male sternite VIII (33, 40); aedeagus in lateral and in ventral view (34–35, 41–42); posteromedian portion of male sternite VII (39); female sternite VIII (43); female tergites IX–X (44–45). Scale bars: 30–31, 36–37: 1.0 mm; 32–35, 38, 40–45: 0.5 mm; 39: 0.2 mm.

Figs 130-139: Lathrobium plicatum sp. n. (130-137) and L. ascendens sp. n. (138-139): habitus (130); forebody (131); male sternite VII (132, 138); male sternite VIII (133); aedeagus in lateral and in ventral view (134-135); female sternite VIII (136, 139); female tergites IX-X (137). Scale bars: 130-131: 1.0 mm; 132-139: 0.5 mm.