Orsunius excisus, Assing, 2011

Assing, V., 2011, Orsunius gen. nov. from the Oriental region (Coleoptera: Staphylinidae: Paederinae: Medonina), Linzer biologische Beiträge 43 (1), pp. 221-244 : 228-229

Orsunius excisus nov.sp. ( Figs 20-26 )

T y p e m a t e r i a l: Holotype Ƌ: " Taiwan - Taitung Co., Rd. No. 20, bfr. Li-Tao (Lidau), km 174, 1000 m, compost, 8.IV.2007, leg. Vít [4] / Holotypus Ƌ Orsunius excisus sp.n. det. V. Assing 2011" (cAss). Paratypes: 1♀: same data as holotype (cAss).

D e s c r i p t i o n: Body length 4.0- 4.8 mm. Coloration: head and pronotum reddish; elytra reddish-yellow, anteriorly or laterally slightly and diffusely darker; abdomen reddish; legs yellowish; antennae reddish-yellow.

Head of transversely rectangular shape, approximately 1.15 times as broad as long ( Fig. 20 ); posterior margin very feebly concave in the middle; punctation moderately coarse and very dense; interstices distinctly narrower than diameter of punctures, reduced to narrow ridges ( Fig. 21 ); sides with numerous long black setae. Eyes large and bulging, slightly longer than postocular portion in dorsal view. Ventral aspect of head with microsculpture; gular sutures anteriorly separated by a distance of slightly less than the width of antennomere III. Antennae with weakly transverse preapical antennomeres.

Pronotum weakly transverse, approximately 1.1 times as wide as long and 1.05 times as broad as head ( Fig. 20 ); posterior angles rounded, weakly marked; lateral margins visible only in posterior two thirds when viewed from above; lateral and anterior margins with numerous long black setae; punctation slightly less coarse and less dense than that of head; impunctate midline reduced, very narrow and reaching neither anterior nor posterior margins ( Fig. 22 ).

Elytra approximately as long as pronotum ( Fig. 20 ); punctation very dense and fine; interstices without microsculpture. Hind wings fully developed. Protarsomeres moderately dilated; metatarsomere I longer than II and slightly shorter than the combined length of II and III.

Abdomen almost as broad as elytra; punctation extremely fine and dense, slightly less dense on tergites VII and VIII; interstices with microsculpture composed of isodiametric and short transverse meshes ( Fig. 23 ); posterior margin of tergite VII with palisade fringe.

Ƌ: sternite VII not distinctly modified; sternite VIII with distinctly excised posterior margin ( Fig. 24 ); aedeagus approximately 0.7 mm long; ventral process large, somewhat asymmetric in ventral view, and with apex of distinctive shape ( Figs 25-26 ).

E t y m o l o g y: The specific epithet (Latin, adjective) alludes to the distinctly excised posterior margin of the male sternite VIII, one of the characters distinguishing O. excisus from its congeners.

C o m p a r a t i v e n o t e s: This species is characterized particularly by the weakly transverse, extremely densely punctate, and rather matt head and pronotum, the shape of the male sternite VIII, as well as by the distinctive shape of the aedeagus.

D i s t r i b u t i o n a n d n a t u r a l h i s t o r y: Thetypelocalityissituatedin southeastern Taiwan. The specimens were sifted from compost at an altitude of 1000 m in April.

Figures

Figs 20-26: Orsunius excisus nov.sp.: (20) forebody; (21) posterior median portion of head in dorsal view; (22) median dorsal portion of pronotum; (23) median portions of abdominal tergites VI and VII; (24) male sternite VIII; (25-26) aedeagus in lateral and in ventral view. Scale bars: 20: 0.5 mm; 24-26: 0.2 mm; 21-23: 0.1 mm.