Clinocercyon, d'Orchymont, 1942

Ryndevich, Sergey K. & Prokin, Alexander A., 2017, Two new species of Cercyon (Clinocercyon) from Russian Far East (Coleoptera: Hydrophilidae), Zootaxa 4300 (1), pp. 125-134 : 133

Key to Palearctic species of Clinocercyon

1. Each elytron yellowish brown, with black sutural interval and a black triangular spot laterally in anterior two thirds of intervals 7–10. Male genitalia (see Jia, Fikáček, Ryndevich, 2011, Figs.1–8 )....................................... C. hanseni

- Elytra without black triangular spots laterally in anterior two thirds of intervals 7–10................................2

2. Preepisternal plate wider, index length/width 2.9–3.8.........................................................3

- Preepisternal plate narrower, index length/width 5.6–7.8.......................................................5

3. Smaller, length 1.9–2.0 mm. Preepisternal elevation wider, index length/width 2.9–3.5. Male genitalia (see Ryndevich, 2007, Figs. 4–6 ).................................................................................. C. rubicundus

- Larger, length 2.4–2.5 mm. Preepisternal elevation narrower, index length/width 3.5–3.8.............................4

4. Elytra blackish brown; elytral suture, sides, apex and humeral tubercles lighter, yellowish brown. Second interval anteriorly markedly wider than the third (starting with elytral suture) and more than twice as wide as first interval......... C. placidus

- Elytra reddish brown to brown, base of elytral suture, humeral tubercles and apex of elytra lighter, yellowish brown. Second interval anteriorly as wide as or slightly narrower than the third, twice as wide as first interval. Male genitalia (see Ryndevich, 2007, Figs. 1–3 ).................................................................................. C. aequalis

5. Head black with brownish spot in middle of the base. Centre of pronotum darkened (brown or blackish) ( Figs. 1, 2 ). Hind femora with distinct microsculpture (as horizontal cells) ( Fig. 5 ). Male genitalia ( Figs. 6–13 )................ C. retius sp. nov.

- Head and pronotum brownish-yellow ( Fig. 14 ). Sometimes anterior and lateral edges of head slightly darker, brownish. Hind femora without microsculpture ( Fig. 17 ). Male genitalia ( Figs. 18–25 )........................... C. primoricus sp. nov.

Figures

FIGURES 1 – 5. Habitus and metafemora of Cercyon retius sp. nov. 1, 2: dorsal view; 3: lateral view; 4: ventral view; 5: metafemora.

FIGURES 6 – 13. Male genitalia of Cercyon retius sp. nov. 6,10: phalobase and parameres; 11: apex of paramere; 7,12: median lobe; 8. apex of median lobe; 9,13: sternite 9. Scale bar = 0.5 mm.

FIGURES 14 – 17. Habitus of Cercyon primoricus sp. nov. 14: dorsal view; 15: ventral view; 16: lateral view; 17: metafemora.

FIGURES 18 – 25. Male genitalia of Cercyon primoricus sp. nov. 18, 22: phalobase and parameres; 23: apex of paramere; 19, 24: median lobe; 20: apex of median lobe; 21, 25: sternite 9. Scale bar = 0.5 mm.