Stenus bostrychus Tang & Puthz

Liang, Tang, Zhao, Yun-Long & Puthz, Volker, 2008, Six new Stenus species of the cirrus group (Coleoptera, Staphylinidae) from China with a key to species of the group, Zootaxa 1745, pp. 1-18 : 12-13

Stenus bostrychus Tang & Puthz , sp. nov.

( Figs. 6 , 30–34 )

Type material. Holotype: CHINA: Sichuan Prov.: ɗ, Luding County, Hailuogou, alt. 2200–2300 m, 27.VII.2006, HU Jia-Yao & TANG Liang leg.( SHNU). Paratypes: CHINA: Sichuan Prov.: 14ɗɗ, 21ΨΨ, same data as for the holotype ( SHNU); 3ɗɗ, 8ΨΨ, Luding County, Hailuogou, alt. 2200–2300 m, 28.VII.2006, HU Jia-Yao & TANG Liang leg. ( SHNU); 2ɗɗ, Ψ, Daxue Shan, Hailuoguo Glaciar Park, Camp 1, 2100 m, 29o36.00’N, 102o03.35’E, 27–31.V.1977, M. Schülke leg. (cPut, cSch).

Description. BL: 4.0– 4.5 mm; FL: 2.1–2.3 mm.

Proportional measurements of holotype: HW: 37, PW: 29, PL: 30, EW: 33.5, EL: 33, SL: 23.5.

Brachypterous, head and abdomen blackish brown, pronotum brown, elytra light brown each with broad and reddish band along lateral side, moderately glossy; head and pronotum moderately coarse and densely punctate, elytra coarsely, rugosely sculptured, abdominal punctation very coarse, dense anteriorly, moderately coarse and moderately dense posteriorly; pubescence long, semierect. Antennae reddish yellow, club infuscate. Maxillary palpi reddish yellow. Legs reddish yellow. Clypeus dark brown, labrum reddish brown, moderately densely pubescent.

Head 1.10 times as wide as elytra; clypeofrontal area densely punctate and pubescent; basiantennal tubercles small; interocular area with deep longitudinal furrows, median portion convex, slightly extending beyond the level of inner eye margins; punctures round to elliptic and partly confluent, larger and sparser on median area than those near inner margins of eyes, diameter of large punctures about as wide as medial cross section of 2nd antennal segment, interstices between punctures smooth, distinctly smaller than half diameter of punctures except along midline where interstices can become as large as diameter of punctures. Antennae when reflexed slightly extending beyond 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 9.0: 5.5: 12.0: 8.0: 7.0: 6.0: 6.0: 4.0: 4.5: 4.5: 6.0. Paraglossae coniform.

Pronotum 1.03 times as long as wide, 0.87 times as wide as elytra, widest near middle and constricted at base; disk uneven, with broad and deep median longitudinal furrow which extends nearly the whole length of pronotum, two impressions in anterior half, two impressions in about middle and two impressions in posterior half; sculpture rugose, punctures confluent, about the same size to those on head, interstices smooth, much smaller than half diameter of punctures.

Elytra nearly as long as wide, distinctly constricted at base, lateral margins gently divergent posteriad; posterior conjoint margins roundly and distinctly emarginate at middle; disk uneven with distinct humeral impression, moderately distinct sutural impression and moderately distinct postero-lateral impression; punctation consisting of longitudinally extended coarse punctures, which are strongly confluent, punctures slightly coarser than on pronotum, interstices smooth, much smaller than half diameter of punctures.

Legs elongate, hind tarsi 0.80 times as long as hind tibiae, 4th tarsomeres strongly bilobed.

Abdomen cylindrical; paratergites very narrow and punctate, present only in 3rd segment, no apical membranous fringe at tergite 7; punctures round to elliptic, gradually becoming smaller posteriad, each puncture with long and suberect seta, interstices smooth, varied from much smaller to a little smaller than diameter of punctures.

Male. Seventh sternite ( Fig. 30 ) impressed at posteromedian part with distinct emargination along posterior margin of impression; 8th sternite ( Fig. 30 ) with narrow and deep emargination at middle of posterior margin; 9th sternite ( Fig. 31 ) with very long apicolateral projections, posterior margin smooth with long serrate median projection. Aedeagus ( Fig. 32 ) stout, median lobe subparallel-sided and well angulate apicolaterally, apical sclerotized area with sinuate hind margin and long and broad projection at middle which is round at apex, expulsion clasp ( Fig. 33 ) large, strongly sclerotized; parameres distinctly longer than median lobe, which are strongly swollen at apex, each with about 14 setae on apico-internal margins.

Female. Abdomen broader than that in male; 8th sternite entire; strongly sclerotized spermatheca as in Fig. 34 , infundibulum conspicuously large.

Remarks. This new species is similar to S. flammeus described from Sichuan Province, but may be distinguished easily by more fuscous coloration, bicolorous elytra, more rugose punctation on pronotum and different sexual characters. Stenus bostrychus differs from all other members of the cirrus group in having coniform paraglossae.

Distribution. China (Sichuan Province).

Etymology. The specific name is derived from the Latin word “ bostrychus ” referring to long and suberect setae on the abdomen.

Figures

FIGURES 1 – 6. Stenus cirrus group, habitus. 1 — S. zhulilongi sp. nov., female; 2 — S. lijinweni sp. nov., male; 3 — S. jiulongshanus sp. nov., male; 4 — S. shenshanjiai sp. nov., male; 5, S. — flammeus sp. nov., male; 6 — S. bostrychus sp. nov., male. Scale bars 1 mm.

FIGURES 30 – 34. Details of Stenus bostrychus sp. nov. 30 — male 7 th – 8 th sternites; 31 — male 9 th sternite; 32 — aedeagus in ventral view; 33 — expulsion clasp of aedeagus; 34 — spermatheca. Scale bars 0.25 mm.