Plastus Plastus tuberculatus Wu & Zhou

Wu, Jie & Zhou, Hong-Zhang, 2010, Taxonomic study of subgenus Plastus s. str. (Coleoptera, Staphylinidae, Osoriinae) in China, with descriptions of five new species, ZooKeys 51, pp. 17-32 : 30-31

Plastus Plastus tuberculatus Wu & Zhou sp. n. Figs 5101520, 21

Type material.

Holotype male, Hainan: Diaoluoshan, 14.i.1985, Gentao Jin and Zurao Liu coll. (SEM-CAS). Paratypes (18 spp.): 11 males, 6 females, same data as for holotype (SEM-CAS); male, Hainan: Limushan: Sanquling, 30.xi.2007, 830 m, Zhuo Yang coll. (IZ-CAS).

Description.

Measurement. Body length: 9.80-10.35 mm. HL: 0.61-0.66 mm; HW: 1.47-1.65 mm; PL: 1.63-1.81 mm; PW: 2.15-2.29 mm; EL: 2.14-2.32 mm; EW: 2.17-2.22 mm.

Coloration. Head black with labrum red-brown (Fig. 10), mandibles black with inner side red-brown. Pronotum and elytra black (Fig. 5). Abdomen black, except for 8th segment slightly rufous. Antennae brown. Femora black, tibiae slightly red-brown. Tarsi slightly yellow-brown.

Structural attributes. Head (Fig. 10) transverse, twice as long as wide, lateral sides slightly concave in middle; frontal impression strongly transverse, about 4 times as wide as long, anterior margin deeply emarginate in middle, with two triangularly convex and pointed frontal teeth at sides, distance between apices of two frontal teeth almost as wide as 3/5 of frontal impression, posterior margin slightly obliquely convergent backwards; lateral teeth straight and blunt, on apical 1/3 of ventral side with distinct pointed subsidiary denticle, on inner side with row of 5-8 long setae extending onto outer base of frontal tooth; lateral impression triangularly and widely depressed at outer base of lateral tooth, bearing 5 or 7 short setae; anterior margin of frontal angle of head slightly convex and depressed inside, forming blunt outer lateral tooth; median sulcus about 1.5 times as long as median length of frontal impression, distinctly divergent posteriorly, almost triangular, the posterior end of which is almost two times as wide as middle; clypeus short and steeply inclined, anterior margin moderately rounded, with 3-5 long setae scattered along lateral side; eye glabrous and strongly convex, occupying about 3/5 of side of head; vertex strongly and tuberculately convex at dorsal base of lateral tooth, gradually inclining in regions near posterior margin of frontal impression, without distinct depression on each side of median sulcus, surface almost polished and covered with fine micropunctures, along lateral and postero-lateral margin with some scattered punctures and long setae, at each side of posterior end of median sulcus with distinct fovea bearing 5-7 setiferous punctures.

Antennae subgeniculate, antennomere I baculiform and apically slightly depressed to form shallow sulcus on dorsal side, antennomere II smallest, slightly transverse; antennomere III elongate about 2 times as long as II; antennomeres IV–X gradually transverse, X about 2.5 times as wide as long; antennomere XI elongate, apically rounded, about 2.5 times as long as X.

Mentum trapeziform (Fig. 15), frontal angle slightly rounded, anterior margin weakly depressed in middle, with indistinct median denticle, ventral surface with three transverse and slightly waved ridges, disc between last posterior ridge and basal margin moderately polished, with 5 or 6 large setiferous punctures.

Pronotum transverse (Fig. 5), distinctly wider than head, anterior margin very weakly bisinuate, sides slightly convergent anteriorly at anterior 1/4; median longitudinal sulcus deep and narrow, slightly broadened at posterior end, not reaching either anterior or posterior margins; lateral marginal area with 30-40 setiferous punctures, punctures on upper half distinctly larger than on those lower half, disc polished, with fine micropuncture evenly distributed.

Protibiae externally furnished with 11-13 denticles, which gradually become shorter basally.

Elytra almost quadrate, epipleural line complete, setiferous punctures on lateral marginal side sparser and less distinct than those on side of pronotum.

Abdomen cylindrical, along anterior and posterior margin of III–VI segments respectively with row of setae, but VI segment with additional median row of setae, segments VII and VIII densely setose, disc of III–VI segment densely punctured, basal distinctly denser than apical, but near posterior margin with small glabrous region in middle, on disc of VII and VIII, glabrous region narrow and extending to basal region.

Male aedeagus almost membranous (Figs 20, 21), basal part of median lobe bulbous and curved behind basal orifice; posterior part baculiform, almost as broad as basal part, sides slightly constricted in middle, distinctly sclerotised on both ventral and lateral sides, with membranous and protruding apex; parameres elongate and weakly curved with apices not extending beyond level of basal protruding apices, slightly broadened near base with anterior margin rounded; basal parts protruding ventrally, apically widely separated below basal orifice.

Remarks.

This species is allied to Plastus Plastus kimurai (Naomi, 1996) in the shape of lateral and outer lateral teeth on head, but can be distinguished from the latter by following features: anterior margin of frontal impression with two distinct frontal teeth, dorsal base of lateral teeth tuberculately convex and median sulcus on head distinctly broadened posteriorly (Fig. 10).

Distribution.

Known from type locality in Hainan, elevation about 800 m.

Etymology.

The species name is derived from Latin word ‘tuberculatus’ (tuberculate) to indicate vertex tuberculately convex at base of lateral teeth.