Ceutorhynchus Germar, 1823

Korotyaev, B. A., 2020, A review of weevils of the genus Ceutorhynchus (Coleoptera: Curculionidae), associated with woodland draba, Draba nemorosa (Brassicaceae), Zoosystematica Rossica (China) 29 (2), pp. 353-367 : 354-357

Genus Ceutorhynchus Germar, 1823

A key to Ceutorhynchus species associated with Draba nemorosa

1 (4). Antennal funicle six-segmented. Claws simple, free, fine, short, moderately divergent (at an angle about 45°). Body small, 1.6–1.9 mm ( Figs 1, 2). Rostrum, antennae, and at least tibiae and tarsi reddish brown, pronotum and elytra black, often with brownish tint. Dorsal vestiture moderately dense, uniform, subrecumbent to semi-erect, formed by narrow parallel-sided whitish scales. Elytral striae bare, intervals not wider than striae, flat or weakly convex. Hind wings non-functional, strongly reduced. Aedeagus angularly narrowed apically ( Figs 11, 12).

2 (3). Elytra narrow, 1.23–1.27 times as long as wide, slightly rounded at sides, flattened dorsally ( Fig. 1). Elytral vestiture subrecumbent. Aedeagus as in Figs 11, 19. Eastern Transcaucasia, Northeastern Turkey.......................... C. gemuricus

3 (2). Elytra wider, oval, 1.08–1.15 times as long as wide, noticeably rounded laterally and convex dorsally ( Figs 2). Elytral vestiture semi-erect. Aedeagus as in Fig. 12, 20. Mountain Caucasus, middle Volga area, Kazakhstan, East Siberia: West Sayan Mts, Buryatia...................... C. kipchak

4 (1). Antennal funicle seven-segmented. Claws simple or toothed, free or closely approximate at base, thin or rather stout, weakly to moderately divergent. Body on overage larger, 1.5–2.5 mm. Body predominantly black, only tibiae may be varyingly dark brown; if legs, apical margin of pronotum and apex of elytra reddish brown, then body robust, claws finely dentate, elytra with white scutellar spot and mottled vestiture of narrow white and brownish scales, and middle tibia of female finely mucronate, anal ventrite deeply depressed medio-apically. Dorsal vestiture sparse to moderately dense, recumbent to semi-erect, uniform and formed by narrow parallel-sided or acuminate white scales, or predominantly by semi-erect dark setae with an admixture of white setiform scales. Elytral striae bare or with white narrow scales, intervals usually wider than striae, flat or barely convex. Hind wings not conspicuously reduced. Aedeagus of varying structure.

5 (8). Larger, 1.8–2.5 mm. Dorsal vestiture quite conspicuous, formed by recumbent uniform greyish narrow truncate scales (then claws distinctly dentate, apical margin of 4th abdominal ventrite entire, and male fore tibia finely mucronate) or by semi-erect dark setae with an admixture of white setiform scales (then claws simple, apical margin of 4th abdominal ventrite shallowly excised medially and slightly raised). Elytral striae with conspicuous narrow white scales. Aedeagus angularly narrowing apically, with sides moderately sclerotised.

6 (7). Dorsal vestiture rather dense, formed by recumbent uniform greyish narrow truncate scales; no trace of white stripes on pronotum or white scutellar spot present ( Fig. 3); sides of mesothorax without condensed white scales on apices of mesepimera. Claws distinctly dentate, apical margin of 4th abdominal ventrite entire, male fore tibia finely mucronate; aedeagus sharpened apically ( Fig. 13). East Siberia, Northeastern Russia (Magadan Prov., Chukchi Autonomous Area), Mongolia, Northern China............................ C. seniculus

7 (6). Dorsal vestitureformedbysubrecumbenttosemierect dark and white very narrow parallel-sided scales; pronotum with narrow median and lateral white stripes; elytra with ill-defined but conspicuous white scutellar spot ( Fig. 4); sides of mesothorax with white scales conspicuously condensed on apices of mesepimera. Claws simple; apical margin of male 4th abdominal ventrite shallowly excised medially and slightly raised; male fore tibia non-mucronate; aedeagus narrowly rounded ( Fig. 14) or shallowly excised apically. Southern East Siberia northward to Yakutia , eastern half of northern Mongolia................ C. klementzorum 8 (5). Smaller, 1.5–2.4 mm. Dorsal vestiture fine, sparse and inconspicuous, elytral striae bare, or elytra with ill-defined white scutellar spot and mottled vestiture of narrow white and brownish scales on intervals and striae with conspicuous lanceolate white scales; 4th abdominal ventrite in male with apical margin not excised medially. Male fore tibia without mucro; female middle tibia finely mucronate, or claws very closely approximate and armed with clearly visible appendage in basal half. 9 (10). Claws very closely approximate and armed with a well-developed tooth in basal half. Rostrum slen- der. Body and legs black, legs may be dark brown. Sides of thorax densely clothed with broad-lanceolate scales separated by less than own width ( Fig. 5). Middle tibia of female non-mucronate. Elytral striae bare, intervals with sparse narrow, parallel-sided white scales. Aedeagus ( Figs 15, 21) with narrowly rounded, weakly attenuate apex. Southern slope of West Sayan, East Tuva Plateau, Central Yakutia (new record)............................................ C. sp. [? C. unguicularis ]

10 (9). Claws weakly diverging, simple or with broad tooth at base [then middle tibia of female finely mucronate, scales on elytral intervals very narrow, pointed apically, legs and partly elytra may be reddish brown (in C. querceti )]. Rostrum wider. Middle tibia of female finely mucronate. Aedeagus with subtruncate or shallowly emarginate apex ( Figs 18, 22, 23).

11 (12). Apical margin of pronotum, legs and at least apical part of elytra reddish brown. Elytra with white scutellar spot and mottled vestiture of narrow white and brownish scales, elytral striae scaled similarly to the intervals ( Fig. 6). Claws dentate at base. Anal ventrite of male very deeply depressed medio-posteriorly, apical margin behind the depression glabrous. Aedeagus as in Fig. 22. Holarctic species, mainly on Rorippa palustris , but found in southern Tuva on Draba nemorosa or D. sibirica .................................... C. querceti

12 (11). Body and legs black, legs occasionally brownish. Elytral vestiture uniform, composed of pointed or parallel-sided very narrow white scales.

13 (14). Claws with short broad tooth at base. Tibiae not paler than femora. Elytral intervals with sparse hair-like pointed scales, striae with similar but shorter scales. White scales on sides of pronotum, meso- and metathorax sparse, separated by not less than own widths; sides of pronotum without conspicuous white stripes. Elytra wider at base and more strongly narrowing toward apex ( Fig. 7). Aedeagus as in Fig. 18. Body length 1.7–2.1 mm. Southern East Siberia east of Lake Baikal, eastern Mongolia, Korean Peninsula. On Draba nemorosa , probably also on Cardamine spp. .... C. dauricus

14 (13). Claws simple. Tibiae often brown. Elytral intervals with sparse parallel-sided, truncate apically white scales; striae bare or with inconspicuous fine hairs. Sides of pronotum without conspicuous white stripes, meso- and metathorax densely clothed with broad white scales separated by less than own widths. Elytra with humeri less convex, widest usually slightly behind them, less rounded at sides and less strongly narrowing toward apex ( Fig. 8). Aedeagus as in Fig. 23. Body length 1.6–2.4 mm. Euro-Siberian species, distributed from West Europe to Irkutsk in the east. Mostly on Cardamine spp. , but found on Draba nemorosa in Irkutsk and on Barbarea arquata south-east of Irkutsk ....................................... C. cochleariae