Cercyon (s. str.) sundukovi, Ryndevich & Hoshina & Prokin, 2019

Ryndevich, S. K., Hoshina, H. & Prokin, A. A., 2019, Review of species of the genus Cercyon of Russia and adjacent regions. VI. Subgenus Cercyon, the C. shinanensis group (Coleoptera: Hydrophilidae), Zoosystematica Rossica (China) 28 (2), pp. 258-266 : 262-265

Cercyon (s. str.) sundukovi sp. nov.

(Figs 8–18)

Holotype. Russia, Sakhalin Prov., Kuril Is., Kunashir I., lower reaches of Saratovskaya Riv., 44°15´46´´N 146°06´13´´E, 12–18.VII.2014, leg. Yu. Sundukov, male ( ZIN).

Paratype. Russia, Sakhalin Prov., Kuril Is., Kunashir I., cordon Alekhinskiy , 43°57´17´´N 145°35´34´´E, 11–14.IX.2014, leg. Yu. Sundukov, female ( CSR) .

Description. Form and colour. Body elongate oval (Fig. 8), length 1.6–1.7 mm, width

Abdomen. Five exposed ventrites; ventrite 1 longest, about twice as long as ventrite 2, bearing distinct median longitudinal carina; ventrite 5 not emarginate apically.

Male genitalia ( Figs 14–18). Phallobase asymmetrical basally, about 1.2 times as long as paramere. Parameres narrowing towards apex, their ventral side membranous, with long setae subapically. Apices of parameres strongly bent in dorsal direction, with very short setae subapically. Median lobe almost parallel-sided, only slightly widened apically, widely rounded at apex, with short apodemes basally; gonopore large, situated subapically. Median projection of sternite 9 narrow; its apex without setae, pointed apically, median portion shorter than lateral struts, base almost direct.

Comparison. This new species differs from C. shinanensis in the darker elytra and in coarser (deeper and larger) punctures on the metaventral median pentagonal area ( Figs 3, 9). In addition, C. shinanensis has the slightly narrower mesoventral plate, about 4.6–5.0 times as long as wide (vs. 4.4–4.5 times in C. sundukovi sp. nov.). The new species also easily differs from C. shinanensis in the paramere narrowing towards the apex, with long setae on ventral side subapically, and the apex strongly bent in the dorsal direction.

Among the South Kuril species, C. sundukovi sp. nov. is similar in colour to C. olibrus Sharp, 1874 , C. rotundulus Sharp, 1884 , and C. saluki Ryndevich, 1998 . Cercyon olibrus differs in the paler head and pronotum, as well as in yellowish brown elytra. Cercyon rotundulus and C. saluki have the broadly oval body, paler head (yellowish brown or reddish brown to dark brown) and the larger size (2.1–2.9 mm).

Cercyon sundukovi sp. nov. is similar to the Palaearctic species C. tristis , C. convexiusculus , C. sternalis and C. subsulcatus in size, colouration and body form, but it can be distinguished from them by the absence of the elytral microsculpture.

Within the genus, the new species also differs from other species in the characteristic structure of the male genitalia: its paramere with long setae subapically and with apex strongly bent in the dorsal direction; the median lobe is almost parallel-sided, only slightly widened apically and widely rounded at the apex.

Etymology. This species is named after the entomologist Yuri Sundukov (Vladivostok, Russia), who collected the type specimens.

Distribution. Kunashir Island, southern Kurils, Russian Far East.

Bionomics. Unknown.