Stenus breviculus Tang & Puthz

Tang, Liang, Li, Li-Zhen & Puthz, Volker, 2010, Five new Stenus species of the cephalotes group (Coleoptera, Staphylinidae) from China with a key to Chinese species of the group, Zootaxa 2335, pp. 29-39 : 32-34

Stenus breviculus Tang & Puthz , sp. nov.

( Figs.2 , 11–15 )

Type material. Holotype: CHINA: Zhejiang Prov.: 3, Qingyuan County, Baishanzu, alt. 1250–1650 m, 21.VIII.2004, HU Jia-Yao, TANG Liang & ZHU Li-Long leg. ( SHNU). Paratypes: CHINA: Zhejiang Prov.: Ƥ, same data as for the holotype ( SHNU).

Description. BL: 2.0– 2.2 mm; FL: 1.1–1.2 mm.

Proportional measurements of holotype: HW: 37.5, PL: 29.0, PW: 27.5, EL: 26.0, EW: 30.0, SL: 20.0.

Brachypterous, moderately glossy, head blackish, pronotum and abdomen dark brown, elytra less dark, chestnut-brown; head moderately coarsely and sparsely punctate, pronotum and elytra coarsely and densely punctate, abdomen moderately coarsely and densely (anteriorly) to finely and very sparsely (posteriorly) punctate; pubescence short, recumbent. Antennae reddish yellow, club infuscate. Maxillary palpi and legs yellowish. Clypeus blackish brown, labrum entirely reddish brown, densely pubescent.

Head 1.25 times as wide as elytra; clypeofrontal area sparsely punctate and pubescent; basiantennal tubercles small; interocular area with deep longitudinal furrows, median portion convex and evenly punctate, elevated a little above the level of inner eye margins; punctures round, well delimited, slightly larger and sparser on median area than those near inner margins of eyes, diameter of punctures about as wide as medial cross section of 3rd antennal segment, interstices densely reticulated, varied from smaller to larger than diameter of punctures. Antennae when reflexed extending a little before posterior margin of pronotum; 3rd to 8th segments much narrower than 2nd; 9th to 11th gradually broadened, forming loose club; relative length of segments from base to apex as 6.0: 4.5: 7.0: 4.0: 4.0: 4.5: 3.0: 2.5: 3.0: 3.5: 5.0. Paraglossae oval.

Pronotum 1.05 times as long as wide, 0.92 times as wide as elytra, widest at a little before middle and constricted at base; disk uneven, with distinct median longitudinal furrow and two indistinct impressions in posterior half; punctation very dense, punctures almost same in size and a little larger than largest punctures on head, interstices densely reticulated, smaller than half diameter of punctures.

Elytra 0.86 times as long as wide, moderately constricted at base, lateral margins gently divergent posteriad, posterior conjoint margins roundly and distinctly emarginate at middle; disk relatively even with shallow longitudinal humeral impression, shallow oblique postero-lateral impression and long and shallow sutural impression; punctuation slightly less dense than that on pronotum.

Legs elongate, hind tarsi 0.68 times as long as hind tibiae, 4th tarsomeres distinctly bilobed.

Abdomen cylindrical; without paratergites except for the trace on basal third of 3rd segment; 7th tergite without apical narrow membranous fringe; punctures round to elliptic, gradually becoming smaller posteriad, interstices faintly microsculptured on 3rd tergite and distinctly sculptured on the rest tergites, varied from smaller to larger than half diameter of punctures.

Male. Eighth sternite ( Fig. 11 ) with round emargination at middle of posterior margin; 9th sternite ( Fig. 12 ) with long apicolateral projections, posterior margin serrate and almost straight. Aedeagus ( Fig. 13 ) slender, median lobe subparallel, apical sclerotized area broad and sinuate at apex; expulsion hooks ( Fig. 14 ) large, internal sac as in the figure 13; parameres extending distinctly beyond the apex of median lobe, slightly swollen at apex, each with 9 subapical setae on its inner side.

Female. Abdomen broader than that in male; 8th sternite with posterior margin slightly pointed at middle; sclerotized spermatheca as in Fig. 15 .

Remarks. This new species can be easily distinguished from other species of the cephalotes group by smaller body.

Distribution. China (Zhejiang Province).

Etymology. The Latin adjective “ breviculus ” refers to the small body size of the new species.

Figures

FIGURES 1 – 5. Stenus cephalotes group, habitus. 1 — S. substrictus sp. nov.; 2 — S. breviculus sp. nov.; 3 — S. gonggashanus sp. nov.; 4 — S. latipectus sp. nov.; 5 — S. tianquanensis sp. nov. Scale bars 1 mm.

FIGURES 11 – 15. Details of Stenus breviculus sp. nov. 11 — male 8 th sternite; 12 — male 9 th sternite; 13 — aedeagus in ventral view; 14 — expulsion clasp of aedeagus; 15 — spermatheca. Scale bars 0.25 mm.