Cybister posticus Aubé, 1838

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 : 95-96

Cybister posticus Aubé, 1838

( Figs 16A–E ; 22B )

Cybister posticus Aubé, 1838: 87 (orig. descr.); JIA et al. (2010): 259 (Xizang: Zayü County).

Material examined. CHINA: XIZANG: 1 J, Mêdog County, Beibeng

Township, 800 m, 5. ix.1974, F. S. Huang leg. ( SYSU); 1 ♀, Bomê

County,Yigong, 1450 m, 9.v.1983,Y.H.Han leg.( SYSU); 1J 1♀, Zayü

County, Xia Zayü, 28.50N 97.00E, 4.–8.x.2007, F. M. Shi leg. ( SYSU).

Diagnosis. TL 23–35 mm, elongate, oblong-oval ( Fig. 16A ). Head dark green, clypeus reddish-brown. 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. 16B ). 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. Forelegs reddish-brown, midlegs and hindlegs reddish-brown to brown; 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. 16C ); broad medially in ventral view, apical fifth slender like a tubular spine, apex rounded ( Fig. 16D ). Parameres moderately broad, strap-like apically ( Fig. 16E ).

Habitat. Although this species is widely distributed in India, nothing is known about its habitat.

Distribution. China (Xizang) ( Fig. 22B ), Bangladesh, India, Nepal, Pakistan (RḖGIMBART 1899, ZIMMERMANN 1920, VAZIRANI 1969, JIA et al. 2010, GHOSH & NILSSON 2012).

Figures

Fig. 16. Cybister posticus Aubé, 1838 (J, Zayü County, Xizang). 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. 22. Map of distribution of Cybister in China.