Stenus aureolus Fauvel, 1875

Shuai, Qi, Tang, Liang & Luo, Yong-Ting, 2020, A review of the Stenus aureolus group of China (Coleoptera: Staphylinidae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 60 (2), pp. 615-627 : 618

Stenus aureolus Fauvel, 1875

( Figs 1 , 11–14 )

Stenus aureolus Fauvel, 1875 : XVII.

Stenus fluviatilis Benick, 1921: 140 : PඎඍΗඓ (1967: 241; synonymized with S. aureolus ).

Stenus ambiseminiger Zhao & Zhou, 2006:286 , syn. nov. (previously erronerously synonymized with S.trigonuroides by PඎඍΗඓ (2008:173)). Material examined. RUSSIA: KΗൺൻൺඋඈඏඌĸ: 1 ♀, Bolshe-Khekhtsyrsky, Reserve, 6–10.vi.1990, 400– 450 m, W. Schawaller leg. (VPSG); 1 J, Slavianka, 20 km N of Troitskoye, 14–19.vi.1990, Amur bank, W. Schawaller leg. (VPSG); 1 J 1 ♀, East Siberia, Irkutsk Territory, Angarsk, 2.vii.2008, I.V. Enustschenko leg. (VPSG); 1 J, East Siberia, Irkutsk Territory, Katangskiy district,Podvoloshino, valley of Nizhnyaya, 4–9.viii.2008, Tunguska R., Shavrin A. & Enustschenko I leg. (VPSG). CHINA: HൾංඅඈඇǤඃංൺඇǤ: 3JJ, Yichun City, Fenlin County, 9.vii.2004, Li-Zhen Li leg. (SHNU); 1 ♀, Yichun, Wuying, Wuying Forest Park, 11.vii.2004, Huang Jia-Jie leg. (SHNU); 1 ♀, Huma County, Houhei Town, 580 m, 15.vii.2009, Li & Liu leg. (SHNU). Jංඅංඇ: 3 JJ 4 ♀♀, Korean pine forest, Mt. Changbai, 23.vii.2004, Li & Huang leg. (SHNU). NൾංආൾඇǤǤඎ: 1 ♀, Hulunbeier City, Erlunchun Ganhe-Kuerbin, 570 m, 16.vii.2009, Li & Liu leg. (SHNU); 1 ♀, Tahe-Mohe County, 500–600 m, 16.vii.2009, Li & Liu leg. (SHNU); 6 JJ 8 ♀♀, Xiaoyangqi Town, Daxing’anling, 9.viii.2011, Xu Wang leg. (SHNU).

Previously published records from China. HൾංඅඈඇǤඃංൺඇǤ: Langxiang, Qingyuan (ZΗൺඈ & ZΗඈඎ 2006, as Stenus ambiseminiger ).

Differential diagnosis. Stenus aureolus Fauvel, 1875 is extremely similar to S. trigonuroides Zheng, 1993 in most aspects. The ratio of HW/EW in S. aureolus is slightly smaller than that of S. trigonuroides . The hind wings of S. aureolus are 1.27–1.39 times as long as elytra, i.e. shorter than those of S trigonuroides (1.88–3.19 times as long as elytra). The aedeagus of S. aureolus ( Fig. 12 ) is almost the same as in S. trigonuroides ( Fig. 16 ), though the length of apical sclerotized area of median lobe is slightly shorter in S. aureolus . The spermathecae of these two species are clearly different: the spermatheca is simple without coiled parts in S. aureolus ( Fig. 14 ), but has complicated coiled parts in S. trigonuroides ( Fig. 18 ). Stenus aureolus is also very similar to S. paratrigonuroides sp. nov. in most aspects. The length of the apical sclerotized area of the median lobe of S. aureolus is slightly shorter and narrower than that of S. paratrigonuroides ( Fig. 39 ). The spermatheca is simple in S. aureolus while it is coiled in S. paratrigonuroides ( Fig. 41 ). Additionally, the distributional ranges of the S. aureolus and S. paratrigonuroides are seperated by that of S. trigonuroides ( Fig. 46 ).

Redescription. Measurements. BL: 3.5–4.2 mm, FL: 1.8–2.1 mm. HW: 0.77–0.87 mm, PL: 0.57–0.68 mm, PW: 0.59–0. 68 mm, EL: 0.76–0.87 mm, EW: 0.77–0.91 mm, SL: 0.56–0.68 mm. Head 0.92–1.01 times as wide as elytra; pronotum 0.93–1.00 times as long as wide; elytra 0.94–0.99 times as long as wide; hind wings 1.27–1.39 times as long as elytra.

Male. Mesotibiae and metatibiae each with a tooth on inner side of apex; sternite VIII with triangular emargination in middle of posterior margin; sternite IX ( Fig. 13 ) with distinct apicolateral projections, posterior margin serrate. Aedeagus ( Figs 11, 12 ) slender; apical sclerotized area of median lobe medium in length and pointed at tip; expulsion clasps slender, strongly sclerotized; copulatory tube long and broad; parameres much longer than median lobe, swollen in apical parts, each with two groups of setae on apico-internal margins: 15–20 setae in distal and 6 or 7 setae in basal group.

Female. Sternite VIII prominent in middle of posterior margin; spermatheca ( Fig. 14 ) sclerotized with basal porch bilobed, spermatheca duct simple without coiled parts, capsule small.

Distribution. China (Heilongjiang, Jilin, Neimenggu), Russia, Mongolia. New species for China.

Remark on synonymy. Stenus ambiseminiger Zhao & Zhou, 2006 was synomized with S. trigonuroides by PඎඍΗඓ (2008). However, the shape of the spermatheca illustrated in the original description of S. ambiseminiger perfectly fits that of S. aureolus . The type locality of S. ambiseminiger (Heilongjiang: Langxiang, Qingyuan) is within the distribution range of S. aureolus . In contrast, S. trigonuroides has not been found in North West China yet. For these reasons, S. ambiseminiger is synomized with S. aureolus .

Figures

Figs 1–5. Habitus. 1 – Stenus aureolus Fauvel, 1875; 2 – S. trigonuroides Zheng, 1993; 3 – S. musicola Cameron, 1930; 4 – S. nigraureolus Ryvkin, 2003; 5 – S. mendaensis sp. nov. Scale bars = 1 mm.

Figs 11–18. Sexual characters. 11–14 – Stenus aureolus Fauvel, 1875; 15–18 – S. trigonuroides Zheng, 1993. 11, 12, 15, 16 – aedeagus; 13, 17 – male sternite IX; 14, 18 – spermatheca. Scale bars = 0.25 mm.

Figs 34–41. Sexual characters. 34–37 – Stenus tenuidentatus sp. nov.; 38–41 – S. paratrigonuroides sp. nov. 34, 35, 38, 39 – aedeagus; 36, 40 – male sternite IX; 37, 41 – spermatheca. Scale bars = 0.25 mm.

Fig. 46. The distribution of the species of the Stenus aureolus group in China.