Stenus bullatus Liu and Tang

Liu, Sheng-Nan & Tang, Liang, 2017, Seven new species of the Stenus cirrus group (Coleoptera, Staphylinidae) from Guangxi, South China, Zootaxa 4268 (2), pp. 238-254 : 240-242

Stenus bullatus Liu and Tang , new species

( Figs 3, 4 , 23–32 )

Type material. CHINA: Guangxi: Holotype: ♂, Mt. Mao’ershan , 25°54'N 110°27'E, alt . 1650 m. 24.VII.2012, HU Jia-Yao & SONG Xiao-Bin leg. (SHNU). Paratupes: 4♂♂3♀♀, alt. 1550–1750 m; 2♂♂2♀♀, alt. 1950–2000 m. (SHNU); 1♂2♀♀, Miaoershan(sic), S slope, 25–26.VII.1997, alt. 1300–2000 m, Bolm lgt (NMPC); 1♀, 20– 27.VII.1997, alt. 800–1300 m, Bolm lgt. (NMPC) Miaoershan is a misspelling of Mao’ershan.

Description. Brachypterous; body blackish, each elytron with a vague orange spot near lateral margin, which is about 3/5 as long as and 2/5 as broad as the respective elytron. Antennae, maxillary palpi and legs yellow except antennal club infuscate. Labrum reddish brown.

BL: 3.6–5.2 mm, FL: 1.8–2.2mm.

HW: 0.73–0.83 mm, PL: 0.56–0.62 mm, PW: 0.53–0.63 mm, EL: 0.61–0.73 mm, EW: 0.62–0.76 mm, SL: 0.47–0.57 mm.

Head 1.09–1.18 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, slightly larger and sparser on median portion than those near inner margins of eyes, diameter of large punctures as wide as apical cross section of antennal segment II; interstices smooth, narrower than half the diameter of punctures. Paraglossae oval.

Pronotum 0.95–1.07 times as long as wide; disk relatively even, without distinct median longitudinal furrow; punctures mostly round, more or less confluent, about the same size to those of head; interstices smooth, much narrower than half the diameter of punctures except for those on actual middle, which may be as wide as the diameter of punctures.

Elytra 0.90–1.07 times as long as wide, disk relatively even; punctures rather confluent, larger than those on pronotum those of head; interstices smooth, much smaller than half diameter of punctures.

Legs with tarsomeres IV strongly bilobed.

Abdomen cylindrical; paratergites very narrow and almost impunctate, present only in segment III, tergites and sternites totally fused in segments IV–VI, posterior margin of tergite VII with indistinct apical membranous fringe; punctation round to elliptic, gradually becoming smaller posteriad; interstices smooth, varied from smaller to larger than diameter of punctures.

Male. Sternite VIII ( Fig. 23 ) with shallow emargination at middle of posterior margin; sternite IX ( Fig. 25 ) with long apicolateral projections, posterior margin serrate variation in one specimen as in Fig. 26 ; tergite X ( Fig. 24 ) with posterior margin truncate and slightly emarginated at middle. Aedeagus ( Figs. 27 ) with apical sclerotized portion triangular and roundly projected at apex; expulsion clasps large, strongly sclerotized, the width of the median lobe varied; parameres distinctly longer than median lobe, swollen at apical parts, each with 12–14 setae on apico-internal margins.

Female. Sternite VIII ( Fig. 30 ) entire; tergite X ( Fig. 31 ) with posterior margin convex; sclerotized spermatheca ( Fig. 32 ) consisting of basal duct, swollen spermatheca duct, RT-duct and capsule.

Distribution. China (Guangxi).

Remarks. This new species is similar to S. zhangdinghengi Pan, Tang & Li 2012 from Guangxi but may be distinguished from the latter by the larger forebody size and ratio of EL/EW (in S. zhangdinghengi BL: 1.6–1.8 mm, EL/EW: 0.72–0.78). The new species is probably related to S. huanghaoi, Tang, Zhao & Li, 2008 from Guangdong by sharing similar sexual characters in both male and female, though it can be easily distinguished from the latter by presence of the elytral spots.

Etymology. The specific name is derived from the Latin word ‘bullatus’, meaning ‘hydatomorphic, vesicular’, referring to the vesicular swollen spermatheca duct.

Figures

FIGURES 3 – 4. Dorsal habitus of Stenus bullatus sp. n. Scale bars: 1 mm.

FIGURES 23 – 32. Diagnostic features of Stenus bullatus. 23. Male sternite VIII. 24 Male tergites IX – X. 25 – 26. Male sternite IX. 27 – 29. Aedeagus, in dorsal view. 30. Female sternite. VIII. 31. Female tergites IX – X. 32. Valvifers and spermatheca. Scale bars: 0.25 mm.