Lathrobium coadultum, Assing, 2015

Assing, Volker, 2015, New species and additional records of Lathrobium and Elytrobium from the Palaearctic region, with special reference to the fauna of East Yunnan (Coleoptera: Staphylinidae: Paederinae), Beiträge Zur Entomologie = Contributions to Entomology 65 (1), pp. 41-74 : 57-59

Lathrobium coadultum spec. nov.

( Figs 63–76 )

Type material: Holotype : “ CHINA [22] – Yunnan, SE Pingbian, primary forest, 22°54'31"N, 103°41'44"E, 2100 m, 27.VIII.2014, M. Schülke / Holotypus  Lathrobium coadultum spec. nov., det. V. Assing 2014” (cAss).

Paratypes: 2 : same data as holotype (cAss, cSch).

Etymology: The specific epithet is the past participle of the Latin verb coadulescere (to grow together) and alludes to the fused female tergites IX and X.

Description: Species of moderate size, without evident sexual size dimorphism; body length 7.0– 7.5 mm; length of forebody 3.5–3.6 mm. Habitus as in Fig. 63 . Coloration: head and pronotum blackish-brown to blackish; elytra dark-brown to blackish-brown, with the posterior portion slightly paler; abdomen dark-brown to blackishbrown; legs and antennae dark-reddish.

Head ( Fig. 64 ) weakly oblong, approximately 1.05 times as long as broad, lateral contours behind eyes distinctly convex; punctation rather dense and coarse in lateral, anterior, and posterior dorsal portions, sparse and finer in median dorsal portion; interstices with conspicuous microreticulation rendering the head nearly matt, on average approximately as broad as diameter of punctures in lateral and posterior dorsal portions ( Fig. 65 ). Eyes weakly convex, weakly projecting from lateral contours of head and small, approximately one-fourth as long as postocular region in dorsal view and composed of slightly more than 50 ommatidia. Antenna 2.0– 2.1 mm long.

Pronotum ( Fig. 64 ) moderately slender, 1.27–1.28 times as long as broad and 1.08–1.10 times as broad as head; punctation slightly coarser than that of head; impunctate midline rather broad; interstices without microsculpture.

Elytra ( Fig. 64 ) short, 0.51–0.52 times as long as pronotum, not distinctly dilated posteriad; humeral angles moderately marked; punctation moderately dense and shallow, weakly defined; interstices without microsculpture. Hind wings completely reduced. Protarsomeres I–IV with weak sexual dimorphism.

Abdomen approximately 1.1 times as broad as elytra; punctation fine, rather dense on tergites III–VII, only slightly less dense on tergite VII than on tergite VI; interstices with shallow transverse microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII with pronounced sexual dimorphism.

: protarsomeres I–IV moderately strongly dilated; tergite VIII with weakly convex posterior margin; sternite VII ( Fig. 70 ) strongly transverse, approximately 1.6 times as broad as long, with rather pronounced and extensive postero-median impression of triangular shape, this impression with a cluster of strongly modified short and stout black setae, median portion with numerous gland openings ( Fig. 71 ), posterior margin weakly concave; sternite VIII ( Fig. 72 ) distinctly oblong, 1.15 times as long as broad, with pronounced median impression in posterior half, this impression with numerous strongly modified short and stout black setae, posterior margin strongly convex, in the middle with small and broadly V-shaped excision; aedeagus ( Figs 66–69 ) 1.7 mm long, slender, and nearly symmetric; ventral process conspicuously long, slender, and apically very acute; dorsal plate long, sclerotized, lamellate, and apically concave in dorsal view, without distinctly separated basal portion; internal sac with two very long and slender sclerotized spines.

: protarsomeres I–IV moderately strongly dilated, only very slightly less so than in male; tergite VIII ( Fig. 73 ) with posterior margin conspicuously acutely produced in the middle; sternite VIII ( Fig. 74 ) elongated, approximately 1.3 times as long as broad and with strongly convex posterior margin; segments IX and X remarkably modified ( Figs 75–76 ): tergites IX (including the posterolateral processes) and X completely fused and forming one long, posteriorly distinctly tapering plate without any sutures whatsoever, apex of this plate reaching far beyond apices of hemi-sternites IX, with two short needle-shaped processes.

Comparative notes: Lathrobium coadultum is distinguished from all other Lathrobium species not only by the distinctive male sexual characters, but also by the shape of the female tergite VIII and above all by the remarkably modified, completely fused female tergites IX and X. Such modifications are unknown from any other species of the genus, suggesting that L. coadultum represents a distinct phylogenetic lineage. This species is additonally separated from other congeners recorded from eastern Yunnan by the more pronounced microreticulation of the head and by the gland openings in the median portion of the male sternite VII.

Distribution and natural history: The type locality and the circumstances of collection are identical to those of L. daweianum .

3.4.2. Other provinces of China

Figures

Figs 54–69: Lathrobium daweianum spec. nov. (54–62) and L. coadultum spec. nov. (63–69): habitus (54, 63); forebody (55, 64); male sternite VII (56); male sternite VIII (57); aedeagus in lateral view (58, 66); internal structures of aedeagus in lateral view (59); female sternite VIII (60); female tergites IX–X (61); female segments IX–X in ventral view (62); median dorsal portion of head (65); aedeagus in dry preparation in lateral, ventral, and dorsal view (67–69). Scale bars: 54–55, 63–64: 1.0 mm; 56–62, 66–69: 0.5 mm; 65: 0.2 mm.

Figs 70–78: Lathrobium coadultum spec. nov.(70–76) and L. rostratum spec. nov.(77–78): male sternite VII (70); median portion of male sternite VII (71); male sternite VIII (72); female tergite VIII (73); female sternite VIII (74, 77); female tergites IX–X (75, 78); female segments IX–X in ventral view (76). Scale bars: 70, 72–78: 0.5 mm; 71: 0.2 mm.