Cybister convexus Sharp, 1882

Jiang, Zhuo-Yin, Zhao, Shuang, Mai, Zu-Qi, Jia, Feng-Long & Hendrich, Lars, 2023, Review of the genus Cybister in China, with description of a new species from Guangdong (Coleoptera: Dytiscidae), Acta Entomologica Musei Nationalis Pragae 63 (1), pp. 75-102 : 93

Cybister convexus Sharp, 1882

( Figs 13A–E ; 18H ; 19E ; 22A )

Cybister convexus Sharp, 1882: 718 (orig. descr.); RḖGIMBART (1899): 353 (Yunnan); FENG (1932): 35 (Yunnan); VAZIRANI (1969): 284 (Yunnan); ZENG (1989): 93 (Yunnan).

Material examined. CHINA: YUNNAN: 1J, Tia Feng on (Grassy hill 3ml. N Yunnanfu). 25.viii.1934, C. Brownell leg. ( SYSU); 1 ♀, Honghe Hani- Yi Autonomous Prefecture, Lvchun County, Niukong Township Section, terrace, 22.9873N, 102.2675E, 1336 m, 30.iv.2021,Z.Y.Jiang, Z.M.Yang, B. P.Huang & Z. Q. Mai leg. ( SYSU); 1 ♀, Dehong Dai Aut. Pref. mount. Range 31 km E Luxi, 2280 m, 24°29′31″N 98°52′58″E, 3.vi.2007, D.W. Wrase leg. ( LHCM); 1 J, Yunnan, Baoshan Pref. mount. Range, 22 km S Tengchong, 1750m, 24°49′29″N 98°29′27″E (in fishpond), 30.viii.2009, D. W. Wrase leg. ( LHCM).

Diagnosis. TL 24–30 mm, elongate, oblong-oval ( Fig. 13A ). Head, pronotum and elytra dark green to black, apex of elytra with reddish-brown spots. Ventral surface black; abdominal ventrites III–IV with a yellow spot on each side ( Fig. 13B ). Head and pronotum smooth, elytra densely covered with conspicuous small granules. Prosternal process lanceolate, with distinct lateral bead, surface flat, apex pointed; lateral parts of metaventrite tongue-shaped, slender, not reaching lateral margins; metacoxal lines distinct, well impressed, nearly parallel medially, divergent anteriorly, along metacoxal lines with a row of punctures. Legs black; protarsomeres 1–3 of male broadly expanded into a palette, with four rows of adhesive setae on their ventral side; male with a single metatarsal claw; female with two metatarsal claws, posterior claw small and sinuate. Median lobe of aedeagus ʻCʼ- shaped in lateral view, slightly curved, broadest at middle, strongly narrowing in apical fifth, apex rounded ( Fig. 13C ); broad medially in ventral view, apical fifth slender like a tubular spine, apex truncated ( Fig. 13D ). Parameres moderately broad, strap-like apically ( Fig. 13E ).

Habitat. The habitat information is not well known for this species. It can be found from hilly to high mountain regions ( ATTHAKOR et al. 2018). In Yunnan, it was collected in a water-filled rut on a forest track from Dehong ( HENDRICH 2008) and in a fish pond. In Lvchun County it was collected at night from terraced fields ( Fig. 18H ).

Distribution. China (Yunnan) ( Fig. 22A ), India, Thailand (RḖGIMBART 1899; ZIMMERMANN 1920; FENG 1932, 1933b; GSCHWENDTNER 1938; VAZIRANI 1969; ZENG 1989; GHOSH & NILSSON 2012; ATTHAKOR et al. 2018).

Figures

Fig. 13. Cybister convexus Sharp, 1882 (J, Kunming, Yunnan). A – habitus in dorsal view; B – habitus in ventral view; C – median lobe of aedeagus in lateral view; D – median lobe of aedeagus in ventral view; E – paramere. Scale bars: 5.0 mm (A, B), 1.0 mm (C–E).

Fig. 18. Habitats of Cybister in China. A–C – lake, Shanxi (C. chinensis); D–E – lowland marsh, Shenzhen, Guangdong (C. rugosus, C. tripunctatus lateralis and C. sugillatus); F – temporary pond in a valley, Danxiashan Mt., Guangdong (C. tripunctatus lateralis and C. limbatus); G – natural pond, Lankeshan Mt., Zhejiang (C. rugosus and C. brevis); H – terraced fields pools, Lvchun County, Yunnan (C. convexus and C. sugillatus).

Fig. 19. Live specimens of Chinese Cybister. A – C. chinensis Motschulsky, 1854 (mating couple); B – C. lateralimarginalis torquatus (Fischer von Waldheim, 1829); C – C. rugosus (W. S. Macleay, 1825); D – C. tripunctatus lateralis (Fabricius, 1798); E – C. convexus Sharp, 1882; F – C. sugillatus Erichson, 1834.

Fig. 22. Map of distribution of Cybister in China.