Priochirus (Eutriacanthus) unicolor Laporte, 1835

Wu, Jie & Zhou, Hong-zhang, 2007, Taxonomy Of The Subgenus Eutriacanthus Jakobson, Of The Genus Priochirus Sharp, From Southern China, With The Description Of Two New Species From Guangxi And Yunnan (Coleoptera: Staphylinidae: Osoriinae), Raffles Bulletin of Zoology 55 (2), pp. 267-276 : 274-276

Priochirus (Eutriacanthus) unicolor Laporte, 1835

( Figs. 16–20 )

Leptochirus unicolor Laporte, 1835: 125 (type locality: Java); Erichson, 1840: 826.

Priochirus unicolor Heller, 1898: 8 ; Bernhauer, 1903: 136; Bernhauer and Schubert, 1910: 16 (subgenus Triacanthochirus ); Scheerpeltz, 1933: 1003; Greenslade, 1971: 138 (subgenus Eutriacanthus ); Herman, 2001: 1141.

Leptochirus coronatus Sachse, 1852: 146 (type locality: Java); Heller, 1898: 8 (synonym of unicolor ); Bernhauer & Schubert, 1910: 16; Herman, 2001: 1141.

Material examined. – 10 males, 13 females, Yunnan, Xishuangbanna, Menglun , 620 m, 12 Feb.2004, Jie Wu & Jiaolin Zhang coll. ( IOZ- CAS) ; 3 males, 4 females, Yunnan, Xishuangbanna, Mengzhe , 11 Jul.1958, Shuyong Wang coll. ( IOZ-CAS) ; 1 male, Sumatra, 1906 (collector unknown) ( IOZ-CAS) .

Redescription. – Body moderately depressed and shiny. Antennae slightly brown; femorae and tibiae slightly redblack, tarsi red-brown; other body parts black.

Head transverse ( Fig. 16 ), parallel-sided, frontal angle weakly convex behind lateral teeth; frontal impression about twice as wide as median length, posterior margin obliquely convergent backwards forming a sharp angle; median tooth triangular and pointed, distinctly shorter than 2 lateral teeth, base convex along central disc of frontal impression and contracted behind anterior margin; lateral teeth apically pointed and curved inwards, lateral face with 6 or 7 setae turning upward, medial face with a bunch of setae just behind anterior margin; median sulcus deep, not anteriorly connected with frontal impression, gradually broadened backwards, posterior end about three times as wide as middle width of median longitudinal sulcus on pronotum; vertex smooth, along lateral and postero-lateral margin with some scattered punctures and setae, posterior margin near to posterior end of sulcus with distinct fovea bearing 3 or 4 setae; clypeus short and declivous anteriorly, anterior margin almost truncate. Eyes glabrous and distinctly convex, longitudinal diameter about 1/2 length of head.

Mandible moderately protruding, anterior half strongly bent, with row of setae along lateral margin, dorsal tooth short and pointed, apically curved inwards; first ventral tooth pointed, strongly convex, medially forming a ridge; second ventral teeth strongly protruding and distinctly concave at apex; behind second ventral teeth, inner margin with small pointed tooth ( Fig. 20 ). Mentum trapeziform and setose, anterior margin laterally convex, median tooth small and pointed; lateral margin convex; surface with distinct transverse ridge, which is strongly convex laterally almost forming 2 denticles ( Fig. 17 ).

Antennae almost reaching base of pronotum posteriorly; 1st segment baculiform, emarginate at apex; 2nd segment transverse; 3rd segment elongate and narrowed at base, about twice as long as 2nd; 4th segment quadrate; 5–10 th segments gradually transverse; 11th segment apically rounded, about twice as long as 10th.

Pronotum distinctly wider than long, anterior margin distinctly bisinuate, sides parallel, posterior margin slightly protruding backwards in middle; surface smooth and shiny with sparse micropunctures; median longitudinal sulcus almost evenly narrowed, not reaching both anterior and posterior margins; disc on each side of sulcus with big puncture; along marginal area with some scattered setiferous punctures, relatively sparser than in other species; lateral line complete on posterior margin of pronotum and reaching basal line. Mesoscutellum tongue-shaped, smooth and shiny.

Protibiae laterally with 15–17 denticles, which gradually becoming shorter basally, on dorsal side with short spine closely behind apical spur. Middle and hind tibiae densely setose.

Elytra slightly wider than long, humeri rounded, almost parallel-sided, combined posterior margins shallowly emarginate; surface shiny with sparse micropunctions; along base and sides with moderately dense setiferous punctures.

Abdomen cylindrical, broadened posteriorly and widest at 7th segment; all segments, except 8th, narrowed at base; surface with sparse setae, relatively dense laterally; punctures big and sparse, denser in basal half of tergites and vanishing in posterior half.

Male: Aedeagus similar to that of P. (E.) tonkinensis , but basal orifice more expanded and rounded; median lobe more bulbous at base, posterior part more broadened in middle, slightly depressed in lateral view; parameres apically pointed, not rounded ( Figs. 18, 19 ).

Measurements. – Body length: 15.0–17.0 mm. HL: 0.93 mm; HW: 15 mm; PL: 2.31 mm; PW: 3.04 mm; EL: 2.81 mm; EW: 2.97 mm (n= 3).

Remarks. – This species is similar to P. pentagonalis Bernhauer, 1914 in shape of median tooth on head, but may be distinguished from the latter by bigger body size and more transverse elytra (not much longer than wide). Before this study, this species has been known only from Indonesia (Java and Sumatra). This is the first time that this species is recorded from southern China and it is possible that this species is more widely distributed in Southeast Asia.

Distribution. – China (Yunnan) and Indonesia.

Figures

Figs. 16–20. Priochirus (Eutriacanthus) unicolor (Laporte, 1835): 16, head and pronotum, dorsal view; 17, mentum; 18, aedeagus, dorsal view; 19, aedeagus, lateral view; 20, left mandible. Scale bars: (Fig. 16) = 1.00 mm; (Figs. 17–20) = 0.25 mm.