Chinese species

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 : 97-99

Key to the Chinese species of Cybister

1 Pronotum and elytra with yellow margins laterally; female with a single metatarsal claw. Subgenus Cybister Curtis, 1827 ....................................................2

– Pronotum and elytra without yellow margins laterally; female with two metatarsal claws. Subgenus Melanectes Brinck, 1945 ....................................... 11

2 Apex of median lobe of aedeagus furcate in ventral view. ....................................................................... 3

– Apex of median lobe of aedeagus not furcate in ventral view. ................................................................. 9

3 Metaventrite and metacoxae black with lateral parts yellow. .................................................................... 4

– Metaventrite and metacoxae entirely black. ........... 7

4 Smaller species, TL: 22–28 mm; female with dorsal surface smooth ( Fig. 3A ). ....................................... 5

– Larger species, TL: 27–33 mm; female dorsal surface with dense longitudinal striae of various lengths on elytra except at its apex ( Fig. 11A ). ....................... 6

5 Smaller species, TL: 22–24 mm; median lobe of aedeagus with apical notch shallower, lateral margins of apex straight and parallel in ventral view ( Fig. 3D ). .................................... C. fumatus Sharp, 1882

– Larger species, TL: 24–28 mm; median lobe of aedeagus with apical notch deeper, lateral margins of apex convex in ventral view ( Fig. 10D ). ................... C. tripunctatus lateralis ( Fabricius, 1798) (partim) and C. laevis Falkenström, 1936

6 Abdominal ventrites III–V black, with lateral yellow spots ( Figs 1B ; 9B ). ...... C. rugosus (W. S. Macleay, 1825) and C. bengalensis Aubé, 1838

– Abdominal ventrites III–V yellowish, with a dark brown band anteriorly ( Fig. 11B ). ............................. ........................................... C. ventralis Sharp, 1882

7 Smaller species, TL 24–28 mm; median lobe of aedeagus with acute-angled apico-medial notch ( Fig. 10D ). ..... C. tripunctatus lateralis ( Fabricius, 1798) (partim)

– Larger species, TL>30.0 mm; median lobe of aedeagus with an obtuse-angled apico-medial notch. ..... 8

8 Median lobe of aedeagus in ventral view with apex and base almost equal in width, lateral margins of apex sinuate, notch of apex shallower ( Fig. 4D ). ...... .............................................. C. guerini Aubé, 1838

– Median lobe of aedeagus in ventral view with apex narrower than base, lateral margins of apex concave, notch of apex deeper ( Fig. 8D ). ................................ ................................... C. limbatus ( Fabricius, 1775)

9 Smaller species, TL: 23–27 mm; ventral surface black with lateral parts of metaventrite and metacoxae reddish-brown ( Fig. 7B ); median lobe of aedeagus slender in ventral view ( Fig. 7D ); female with dorsal surface smooth. ..................................... ........................................ C. lewisianus Sharp, 1873

– Larger species, TL> 29 mm; ventral surface yellow with middle parts of metaventrite and metacoxae reddish-brown or dark green; median lobe of aedeagus thick in ventral view; female dorsal surface with isolated short, irregular striae on pronotum, and with dense longitudinal striae of various lengths on elytra except at its apex. ................................................. 10

Figures

Fig. 3. Cybister fumatus Sharp, 1882 (J♀, Laos). 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. 11. Cybister ventralis Sharp, 1882 (J♀, Pusa, Bihar, India). 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. 10. Cybister tripunctatus lateralis (Fabricius, 1798) (J, Guangzhou, Guangdong).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. 1. Cybister bengalensis Aubé, 1838 (J, Ku Sia, Taiwan). 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. 9. Cybister rugosus (W. S. Macleay, 1825) (J, Fengkai County, Guangdong). 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. 4. Cybister guerini Aubé, 1838 (J, Guangzhou, Guangdong).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. 8. Cybister limbatus (Fabricius, 1775) (J, Guangzhou, Guangdong). 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. 7. Cybister lewisianus Sharp, 1873 (J, Guangzhou, Guangdong).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).