Stenus trigonuroides Zheng, 1993

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 : 618-620

Stenus trigonuroides Zheng, 1993

( Figs 2 , 15–18 )

Stenus trigonuroides Zheng, 1993: 229 : PඎඍΗඓ (2008: 173); TൺඇǤ &

Lං (2013: 4). Type material examined. Pൺඋൺඍඒඉൾ: CHINA: SංർΗඎൺඇ: 1♀, Emeishan,

near Jinding, 26.vii.1983 (label written in Chinese, VPSG).

Additional material examined. CHINA: SංർΗඎൺඇ: 12 JJ 9 ♀♀, Emeishan, Jinding, 29°31’N, 103°20’E, alt 3000 m, 20.vii.2012, Peng, Dai & Yin leg. ( SHNU); 2 ♀♀, Ganzi Tibetian Auton Pref., Batang Co., Shaluli Shan, Abies -Forest, 55 km NE Batang, 30°07′68″N, 100°03′77″E, 4200 m, 3.vii.1999, A. Pütz leg. ( APEG); 1 J 1♀, Ya’an Pref., Shimian Co., Xiaoxiang Ling, Pass between Shimian-Ganluo, 27 km SE Shimian, 2450 m, 29°02′75″N, 102°31′48″E, springfed-swamp, 8.vii.1999, A. Pütz leg. ( APEG); 2 ♀♀, 20 km W of Luhua, 2750–3200 m, mixed forest, 8–28.vi.2004, R. Fabbri leg. ( MSBG); 1 J, Ya’an Prefecture, Shimian Co., Xiaoxiang Ling, Pass zw., Shimian u., Ganluo [= pass between Shimian and Ganluo], 27 km SE Shimian, 29°03′N, 102°31′E, 2450 m, Quellsumpf, Bachufer [= headspring wetland, streamside], 8.vii.1999, M. Schülke leg. ( MSBG); 1 J, YanYuan, Chuandongzi-Massif, 27°20′22″N, 101°32′43″E, 4100 m, 9–19.vi.2017, Reuter leg. ( BFMG). NංඇǤඑංൺ: 2 JJ 2 ♀♀, Jinyuan County, Fengtai Lingchang, alt. 2310 m, 22–28.vi.2008, Yin Zi-Wei leg. ( SHNU). SΗൺൺඇඑං: 2 JJ, Foping, alt. 1400–1800 m, 19.vii.2004, Hu, Tang & Zhu leg. ( SHNU). QංඇǤΗൺං: 1 J, Menda N. R., alt. 2200–2500 m, Hu, Tang & Zhu leg. ( SHNU); 1 J, Lang Shi Dang Jing Qu Park, 75km NW Honggu, 2925 m, 36°54′05.2″N, 102°21′07.1″E, creek valley on overgrown scree, Populus and Betula forest with Rhododendron , litter sifted between rocks, 28.vi.2011, M. Schülke leg. ( MSBG); 1 ♀, road 301 km, 180.43 km ESE Men Yuan, 2704 m, 37°09′32.6″N, 102°02′06.0″E, creek valley with Picea, Salix , Populus , Betula , litter and moss sifted, 5.vii.2011, M. Schülke leg. ( MSBG). Gൺඇඌඎ: 1 ♀, ‘Mts.ʼ [the name of the mountains is not provided on the label], 25km E Xiahe, 2805–2925 m, 3.viii.1994,A. Smetana leg. ( ASTJ); 3 ♀♀, Xinlong shan, cca 70 km of Lanzhou, 2225–2380 m, 7.viii.1994, A. Smetana leg. ( ASTJ); 1 J, Xiahe env., 35°11.5′N, 102°30.6′E, 2940 m, 19–22.vi.2005, J. Hájek, D. Král & J. Růžička leg. ( NMPC); 1 J, Min Shan, 45km SW Longnan, 2200 m, 33°03′13″N, 104°40′57″E, (secondary pine forest with hazelnut, moist litter/moss/soil sifted), 6.viii.2012, D. W. Wrase leg. ( MSBG); 1 J, Mts., 38km SE Longnan, 2060 m, 33°11′20″N, 105°14′24″E, (W slope with scree/scrubs/tall herbaceous vegetation, roots/soil/moss sifted), 7.viii.2012, D. W. Wrase leg. ( MSBG).

Previously published records from China. SංർΗඎൺඇ: Wolong and Mt. Emei (ZΗൾඇǤ 1993). NංඇǤඑංൺ: Jinyuan (TൺඇǤ & Lං 2013).

Differential diagnosis. The species is extremly similar to S. aureolus distributed in the Russian Far East and northern China, and to S. paratrigonuroides sp. nov. distributed in Yunnan ( Fig. 46 ). The differences between appearances of the three species can be hardly noticed: the ratio of HW/ EW of S. trigonuroides is in average slightly smaller than those of S. aureolus and S. paratrigonuroides . Hind wings of S. trigonuroides are distinctly longer (1.88–3.19 times as long as elytra) than those of S. aureolus (1.27–1.39 times as long as elytra) and S. paratrigonuroides (slightly longer than half the elytra). For an accurate identification, genitalia dissection is necessary. The apical sclerotized area of the median lobe in S. trigonuroides ( Fig. 16 ) is longer than that in S. aureolus ( Fig. 12 ) and relatively wider and shorter than that of S. paratrigonuroides ( Fig. 39 ). The spermatheca of S. trigonuroides ( Fig. 18 ) is more complicated than that of S. aureolus ( Fig. 14 ), with coiled tube at the first bend.

Redescription. Measurements. BL: 3.4–4.5 mm, FL: 1.8–2.2 mm. HW: 0.76–0.87 mm, PL: 0.57–0.67 mm, PW: 0.59–0.67 mm, EL: 0.78–0.97 mm, EW: 0.75–0.98 mm, SL: 0.58–0.76 mm. Head 0.83–0.96 times as wide as elytra; pronotum 0.94–1.03 times as long as wide; elytra 0.94–1.02 times as long as wide; hind wings 1.88–3.19 times as long as elytra.

Male. Mesotibiae and metatibiae each with tooth on inner side of apex; sternite VIII with triangular emargination in middle of posterior margin; sternite IX ( Fig. 17 ) with distinct apicolateral projections, posterior margin serrate. Aedeagus ( Figs 15, 16 ) 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: 14–18 setae in distal and 6 setae in basal group.

Female. Sternite VIII prominent in middle of posterior margin; spermatheca ( Fig. 18 ) sclerotized with basal porch bilobed, spermatheca duct coiled at first bend, capsule small.

Distribution. China (Sichuan, Ningxia, Shaanxi, Qinghai, Gansu). New to Shaanxi, Qinghai and Gansu.

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.

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

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.