Stenus xichangensis Tang, Liu & Dong, 2018

Tang, Liang, Liu, Sheng-Nan & Dong, Xin-Yu, 2018, Seven new species of the Stenus cirrus group (Coleoptera, Staphylinidae) from Sichuan, Southwest China, Zootaxa 4425 (3), pp. 527-540 : 536

Stenus xichangensis Tang, Liu & Dong , new species

(Figs 6, 40–43)

Material examined. Holotype: ♂, glued on a card with labels as follows: “ China S. Sichian. S. Xichang, Mt. Luoji , alt. 2300–2500 m, litter . 16-24.VII.1996, Kurbatov leg”. “Holotype / Stenus xichangensis / Tang, Liu & Dong” [red handwritten label] (MHNG). Paratypes: 1♂, same data as for the holotype. ( MHNG).

Description. Brachypterous; head reddish brown posterior portion along the inner eye margins darker, pronotum and elytra reddish brown with midline broadly darker, abdomen dark with lateral portions lighter. Antennae, maxillary palpi and legs yellowish brown except antennal club and tarsomeres I–IV infuscate.

BL: 4.1–4.5 mm, FL: 1.8–1.9 mm.

HW: 0.81 mm, PL: 0.63 mm, PW: 0.69 mm, EL: 0.62–0.64 mm, EW: 0.82–0.85 mm, SL: 0.47–0.48 mm.

Head 0.96–0.99 times as wide as elytra; interocular area with two deep longitudinal furrows, median portion convex, slightly extending beyond the level of inner eye margins; punctures round, more or less confluent, similar in size, diameter of punctures about as wide as apical cross section of antennal segment II; interstices mostly smooth, few reticulated, much narrower than half the diameter of punctures except those along the midline of the convex median portion, which may be as wide as diameter of punctures. Paraglossa oval.

Pronotum 0.90 times as long as wide; disk uneven, with distinct median longitudinal furrow, two impressions in anterior half, transverse impression in the middle, and two impressions in posterior half, four humps near lateral sides of the anterior and posterior impressions distinct; punctures strongly confluent, slightly smaller than those of head; interstices ridge like, reticulated (in another specimen, interstices at the central of median longitudinal furrow smooth), mostly narrower than half the diameter of punctures except those in median area, which may be as wide as diameter of punctures (in another specimen, three times wider than diameter of punctures).

Elytra 0.75–0.76 times as long as wide; disk uneven with distinct longitudinal humeral impression, distinct postero-lateral impression and long sutural impression, suture moderately convex; punctation longitudinally confluent, a little larger than those of pronotum, interstices similar to those of pronotum.

Legs rather stout with tarsomeres IV deeply bilobed.

Abdomen cylindrical; paratergites very narrow and almost impunctate, present only in segment III, tergites and sternites totally fused in segments IV–VI though traces of degenerated paratergites can be recognized in basal half of segments IV and V; posterior margin of tergite VII without apical membranous fringe; punctation round and shallow, gradually becoming smaller and sparser posteriad; interstices smooth on tergites III–VIII and reticulated on last two tergites, mostly narrower than diameter of punctures and those on basal impressions of tergites III–V could be distinctly narrower than half the diameter of punctures.

Male. Sternite VII with emargination at middle of posterior margin and a distinct impression before it; sternite VIII ( Fig. 40 ) with distinct semi-circular emargination at middle of posterior margin; sternite IX ( Fig. 41 ) with long apicolateral projections, posterior margin strongly serrate. Aedeagus ( Figs. 42–43 ) with median lobe robust, apical sclerotized area roundly poited at apex with a broad mid groove; expulsion plate with two posterior projections; parameres slightly shorter than median lobe, swollen and folded at apical fourth, each with 15–18 setae on apicointernal margins.

Female. Unknown.

Distribution. China (Sichuan).

Remarks. The species can be readily distinguished from other species of the cirrus group by sturdy body form and the unique coloration.

Etymology. The specific name is derived from the type locality of this species.

Figures

FIGURES 40–43. Stenus xichangensis. 40 male sternite VIII 41 male sternite IX 42, 43 aedeagus. Scale bars: 0.25 mm.