Priochirus (Euleptarthrus) deltodontus

Wu, Jie & Zhou, Hong-Zhang, 2013, Taxonomy of the subgenus Euleptarthrus Jakobson (Coleoptera, Staphylinidae, Osoriinae, Priochirus) of China with descriptions of three new species, Zootaxa 3613 (2), pp. 165-175 : 170-171

Priochirus (Euleptarthrus) deltodontus Wu & Zhou, new species

( Figs. 6–10 )

Type material. Holotype. CHINA: Yunnan: 3, Pingbian, Shuiweicheng, 2100 m, decaying log, 21.v.2009, Jie Wu coll. (SEM-CAS). Paratypes: CHINA: Yunnan: 3, Ƥ, same data as holotype (SEM-CAS); 2Ƥ, same locality, 2025 m, 20.v.2009, Jie Wu coll. (SEM-CAS).

Description. Body length 7.7–9.8 mm. HL 0.58–0.60 mm, HW 1.18–1.24 mm, PL 1.23–1.38 mm, PW 1.72–1.90 mm, EL 1.70–1.78 mm, EW 1.74–1.86 mm.

Coloration. Head black with mouthparts red-brown. Pronotum black, except for posterior margine dark red. Elytra dark red. Abdomen black except for posterior margine of 3th–6th segments red-brown, posterior 1/6 of 7th and whole of 8th segments dark rufous. Antennae red-brown. Femora and tibiae dark red, tarsi slightly rufous.

Head ( Fig. 6 ) strongly transverse, about twice as wide as long, sides almost parallel; frontal impression deep, longer than wide, distinctly narrowed frontad, width of its anterior margin about 1/6 times head width; median sulcus broadly connected with frontal impression and sharply contracted posteriorly, its lateral margins almost fused at posterior margin of head; inner lateral teeth distinctly convex and triangularly pointed, outer lateral teeth blunt and moderately rounded, almost as long as inner teeth, lateral impression between inner and outer lateral teeth longitudinally depressed; frontal angle of head distinctly convex and rounded; vertex distinctly covered with fine coriaceous ground sculpture, row of long setae along postero-lateral margin; eyes distinctly convex, almost 1/ 2 as long as side of head. Clypeus steep, anterior margin slightly truncated, disc in center with two very close pairs of long setae, each baso-lateral side of clypeus with pair of long setae.

Mandibles ( Fig. 7 ) almost symmetrical, moderately protruding, outer surface almost straight along basal 2/3, 1st dorsal tooth short and apically introflexed, 2nd dorsal tooth absent, apical tooth small with long seta close to its inner base, 1st and 2nd ventral teeth basally contracted to form bifurcate structure, behind which the mandible inner margin straight, 3rd ventral tooth absent.

Mentum ( Fig. 8 ) trapeziform, lateral margin ventrally convex, interrupted at frontal angle, anterior margin not convex and broadly depressed in middle; median denticle distinctly projecting and deeply emarginate at apex, ventrally without keel; ventral surface rugose, basal impression elliptic and shallowly depressed bearing 3 basal setae, in central disc with long median seta, without distinct impression in anterior half; 6 anterior setae arranged in row and extending to midline.

Antennae long, weakly geniculate, posteriorly reaching shoulder of elytra, 1st segment baculiform, apically emarginate, dorsally without sulcus, 2nd smallest, slightly longer than wide, 3rd elongate and narrowed at base, about 2 times as long as 2nd, 4th and 5th slightly elongate ellipsoid, 6th–7th slightly longer than wide, 8th quadrate, 9 and 10th slightly transverse, 11th elongate, bluntly pointed, about two times as long as 10th.

Pronotum slightly transverse, anterior margin weakly sinuate, lateral sides almost parallel, posterior margin moderately protruding medio-posteriorly; superior marginal line only extending to postero-lateral angle of pronotum; disc surface with distinct coriaceous ground sculpture, setiferous punctures sporadically scattered along superior marginal line, above these punctures, in anterior 1/3 of lateral marginal area with big setiferous punctures; median longitudinal sulcus very narrow, distinctly expanding at posterior end to form fovea.

Protibiae crenulate externally, with 14–17 denticles, 2nd one distinctly smaller than 1st and 3rd.

Elytra almost quadrate, sides slightly convex posteriorly, surface covered with coriaceus ground sculpture more distinctly than on pronotum and head; along lateral margin with several sparsely scattered small setiferous punctures.

Abdomen cylindrical, weakly broadened posteriorly; surface of 3th–6th segments basally with dense isolated micropunctures, unpunctated regions with indistinct coriaceous sculpture; 3rd segment with row of posterior setae, 4-6th segments with two rows of setae, one along basal and the other along posterior margin, posterior setae longer and denser than basal; 7th and 8th segments with dense setae, except for glabrous median part.

Male aedeagus almost membranous ( Figs. 9, 10 ) with median lobe distinctly bulbous at base, slightly constricted and squarely curved behind basal orifice, posterior part baculiform, weakly and narrowly sclerotised on the dorsal side; parameres thin and weakly curved with their basal parts protruding ventrally and connected to each other, in dorsal view the protrusion truncated anteriorly; basal orifice rounded distally.

Remarks. The new species is similar to P. (E.) amblyodontus in mandible shape and body size, but can be easily distinguished from the latter by triangular inner lateral teeth, narrower frontal impression, and dark red colour of elytra.

Distribution. Known only from the type locality in Yunnan, at elevations of 2025–2100 m.

Etymology. The species name is a combination of the Greek words ‘delta’ (triangular) and ‘odontos’ (tooth) to indicate the shape of the inner lateral teeth on the head.

Figures

FIGURES 6 – 10. Priochirus deltodontus sp. nov. 6, dorsal view of head and prothorax; 7, dorsal view of left mandible (broken line indicating unobserved part); 8, mentum (wrinkles and rugae on surface not shown); 9, ventral view of male aedeagus; 10, lateral view of male aedeagus. Scale bars: 0.25 mm.