Lathrobium rostratum, 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 : 52

Lathrobium rostratum spec. nov.

( Figs 30–35 , 77–78 )

Type material: Holotype : “ CHINA [6] – Yunnan, NE Kunming, 25°08'35"N, 102°53'49"E, 2320 m, mixed forest, sifted, 13.VIII.2014, V. Assing / Holotypus  Lathrobium rostratum spec. nov., det. V. Assing 2014” (cAss).

Paratypes: 9 , 7  [2 , 2  teneral]: same data as holotype (cAss, MNHUB); 3 , 4  [1 teneral]: same data as holotype, but leg. M. Schülke (cSch); 3 , 3 : “ CHINA [5] – Yunnan, NE Kunming, 25°08'40"N, 102°53'48"E, 2290 m, mixed forest, sifted, 11.VIII.2014, V. Assing” (cAss); 2  [1 teneral], same data, but leg. M. Schülke (cSch) .

Etymology: The specific epithet is an adjective derived from the Latin noun rostrum (beak) and alludes to the shape of the apex of the aedeagus.

Description: Species of moderate size, without evident sexual size dimorphism; body length 6.5–8.2 mm; length of forebody 3.3–3.7 mm. Habitus as in Fig. 30 . Coloration: body black; legs brown, with the profemora and often also the meso- and metafemora dark-brown and with the tarsi yellowish-brown; antennae reddish.

Head ( Fig. 31 ) weakly transverse, 1.01–1.04 times as broad as long, usually weakly dilated behind eyes; punctation rather sparse, in median dorsal portion even sparser, and moderately coarse to moderately fine; interstices with distinct microreticulation, on average distinctly broader than diameter of punctures in lateral and posterior dorsal portions. Eyes weakly convex, weakly projecting from lateral contours of head and of moderate size, approximately one-third as long as postocular region in dorsal view and composed of slightly more than 50 ommatidia. Antenna 1.8–2.0 mm long.

Pronotum ( Fig. 31 ) rather broad and relatively weakly oblong, approximately 1.15 times as long as broad and approximately 1.1 times as broad as head; punctation usually slightly coarser than that of head; impunctate midline moderately broad; interstices without microsculpture.

Elytra ( Fig. 31 ) short and broad, approximately 1.75 times as broad (combined width) as long and 0.52–0.54 times as long as pronotum, not distinctly dilated posteriad; humeral angles moderately marked; punctation moderately dense, shallower and usually finer than that of pronotum; interstices without microsculpture. Hind wings completely reduced. Protarsomeres I–IV with moderately pronounced sexual dimorphism.

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

: protarsomeres I–IV distinctly dilated; posterior margin of tergite VIII very obtusely angled in the middle; sternite VII ( Fig. 32 ) distinctly transverse, approximately 1.55 times as broad as long, posteriorly with shallow and rather small median impression and with broadly and weakly concave posterior margin, pubescence not distinctly modified; sternite VIII ( Fig. 33 ) approximately as broad as long, posteriorly with excision of trapezoid shape, on either side of this excision with an ill-defined cluster of moderately modified black setae; aedeagus ( Figs 34–35 ) approximately 1.2 mm long, slightly asymmetric, dorso-ventrally depressed, weakly sclerotized apically, and with small basal portion; ventral process slightly asymmetric, apically deeply bifid, the apices shaped like lamellae; dorsal plate weakly sclerotized, truncate basally and apically, and without separate basal portion; internal sac with an irregular membranous ringshaped structure, without additional structures.

: protarsomeres I–IV dilated, but somewhat less so than in male; posterior margin of tergite VIII distinctly angled in the middle (more so than in male); sternite VIII ( Fig. 77 ) approximately 1.1 times as long as broad and with strongly convex posterior margin; tergite IX ( Fig. 78 ) with short antero-median portion with median suture and with slender postero-lateral processes; tergite X ( Fig. 78 ) flattened and very long, approximately five times as long as antero-median portion of tergite IX.

Comparative notes: As can be inferred from the external and sexual characters, particularly from the similarly modified aedeagus, L. rostratum , too, belongs to the L. tentaculatum group. It is distinguished from L. crenatum by slightly smaller body size, distinctly smaller eyes, the shapes and chaetotaxy of the male sternites VII and VIII, the shape of the aedeagus, and by the long antero-median portion of the female tergite IX.

Distribution and natural history: The species was found in two geographically close localities to the northeast of Kunming. The specimens were sifted from litter in a mixed broad-leaved forest with scattered pine trees and in a mixed forest with alder, oak, and pine at altitudes of 2290 and 2320 m, respectively. Some of the paratypes are teneral.

Figures

Figs 21–35: Lathrobium crenatum spec. nov. (21–29) and L. rostratum spec. nov. (30–35): habitus (21, 30); forebody (22, 31); male sternite VII (23, 32); male sternite VIII (24, 33); aedeagus in ventral view (25, 35); aedeagus in dry preparation in ventral and in dorsal view (26–27); female sternite VIII (28); female tergites IX–X (29); aedeagus in lateral view (34). Scale bars: 21–22, 30–31: 1.0 mm; 23–29, 32–35: 0.5 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.