Ceutorhynchus melniki, Korotyaev, 2020

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 : 363-364

Ceutorhynchus melniki sp. nov.

( Figs 16, 25, 28)

Ceutorhynchus unguicularis : Korotyaev, 1980: 160, pro parte (female from Mongolia), nec C.G. Thompson, 1871 (misidentification).

Holotype, male: Russia, Primorskiy Terr., 20 km E of Khasan, Golubinyy Utyos Rock , 42°24′51″N, 130°44′54″E, 1–8.VII.2000, I. V. Melnik leg.

Paratypes. Russia: Primorskiy Terr., 5 km NW of Lake Khanka , 22 km SW of Turii Rog Vill., 2.VII.1974, A.B. Egorov leg., 1 female ; Zabaikalskiy Terr., 30 km NE of Borzya Stn , 6.VII.1989, O.N. Kabakov leg., 1 female . Mongolia, East Aimak, 50 km ENE of Mt. Ikh- Chulut-Ula, old Somon Matad , 22.VI.1976, E.L. Gurjeva leg., 1 female .

Description. Male. Rostrum 1.39 times as long as pronotum, subcylindrical, slightly widening toward base in basal one-third, regularly and rather strongly curved, as wide as middle part of fore tibia. Base of rostrum levelling with frons. Dorsal surface of rostrum in basal one-third almost matt, densely covered with oblong, rather shallow punctures partly merging in fine striae along obtuse low median carina closer to middle third; latter with finer striolate punctation thinning apically; apical one-third shining, with sparse fine punctures. Antennae inserted at 0.49 length of rostrum from base. Scape weakly widening in apical one-third. Funicle seven-segmented, fine and rather long; 1st segment 2.8 times as long as wide, weakly widening apically; 2nd segment 0.75 times as long as 1st, about triple as long as wide; 3rd segment two-thirds as long as 2nd; 4–6th segments of subequal lengths, noticeably shorter than 3rd segment, more than twice as long as wide; 7th segment distinctly shorter than 6th, about as long as wide. Club terete, almost symmetrical, moderately long, 2.4 times as long as wide, narrow at apex, matt, very densely covered with short fine pubescence. Sutures between segments of club not very conspicuous, only the distal to mid-length onebeing quite distinct. Funicle bearing sparse short, fine, semi-erect hairs. Frons flat, moderately widening posteriorly. Head capsule matt, densely covered with medium-sized, moderately deep polygonal punctures, vertex not carinate. Eyes medium-sized, almost round except for rectilinear anterior margin touching base of rostrum laterally. Dorsal margin of eye situated below frons margin in lateral view.

Pronotum moderately transverse, 1.35 times as wide as long. Base shallowly bisinuate, weakly angularly protruding posteriorly in the middle. Sides rounded, convexly converging to the moderately deep apical constriction separating moderately long apical part (“collar”) narrowing anteriorly. Lateral tubercles small, obtuse, not protruding from pronotum outline. Disc moderately and rather evenly convex, its sides in anterior half moderately obliquely depressed; median sulcus obsolete in the middle, shallow and wide, rounded at base, narrower at apical constriction. Apical margin of pronotum weakly raised, weakly roundly protruding anteriorly, with shallow emargination in the medial third limited by two weak obtuse angulations; emargination somewhat narrower than frons at posterior margin. Surface of disc almost matt, with very dense small, rather deep punctures separated by narrow but flat, shining in a few places intervals.

Scutellum very small and narrow, convex, shining. Apices of mesepimera clearly visible dorsally.

Elytra 1.25 times as long as wide, 1.37 times as wide as pronotum, with moderately convex humeral prominences. Sides subparallel in basal half, without depressions behind humeri, moderately and rather smoothly converging in apical half toward ill-defined, almost smoothened preapical prominences bearing rather sparse, small, acute granules not arranged in crests. Disc moderately and rather evenly convex, slightly flattened in basal half but not depressed behind scutellum. Striae moderately wide and deep; dense, almost round punctures in them slightly excising margins of intervals. The latter about 1.5 times as wide as striae, flat, weakly shining, with irregular fine punctures and small rounded, flattened, low granules.

Legs rather long and slender; femora mutic, weakly S-curved, weekly widened in middle part. Fore tibia non-mucronate, weakly S-curved, weakly widening along most of length and noticeably shortly outcurved and widened at apex; spines in apical comb very fine and dense. Middle and hind tibiae with sharp short mucro, weakly S-curved, moderately roundly and shortly widened at apex, with slightly longer fine setae in apical comb. Tarsi moderately long and rather narrow; 1st segment about 1.5 times as long as wide, 2nd segment in fore tarsus 1.4 times as long as wide, in middle and hind tarsi slightly shorter; 3rd segment 0.8 times as long and almost twice (1.82 times) as wide as 2nd. Claw-segment weakly widening apically, by 0.6 extending beyond lobes of 3rd segment. Claws short, weakly divergent, with well visible subconnate appendages in basal half. Anal ventrite shallowly depressed in medial third along its entire length, sides of the depression weakly, obtusely convex in apical part. Pygidium almost twice as wide as long, weakly convex, neither sulcate nor carinate, matt, densely rugosely punctate. Aedeagus ( Figs 16, 25) much longer and narrower than in C. unguicularis , subparallel-sided, shortly narrowly rounded apically, with sclerotised lateral areas narrow and developed only in apical two-thirds.

Body black, only antennae and 3rd tarsal segment very dark brown. Rostrum with sparse short narrow, posteriorly-pointed recumbent greyish scales along sides in basal quarter. Head capsule with moderately dense narrow subrecumbent, posteriorly-pointed greyish (along eyes margins) and brownish scales. Pronotum and elytra with moderately dense narrow, parallel-sided or somewhat narrowing apically truncate, subrecumbent (on pronotum) or recumbent (on elytral intervals) light brownish scales. In addition, pronotum with a row of small lanceolate white scales along base and along median line; elytra also with a few such scales at bases of 1st and 2nd intervals and with wider scales in mid-length one-third of lateral interval. Underside with almost uniform vestiture of wider short-lanceolate white scales separated mostly by own widths. Depression on anal ventrite in posterior two-thirds densely covered with white scales, especially at sides, and with fine pale erect setae at posterior margin. Pygidium lacking white scales, with moderately dense, long, fine, subrecumbent yellow and white (at sides) hairs.

Female. Rostrum 1.37–1.48 times as long as pronotum, strongly and evenly curved. Basal part of rostrum moderately shining, finely punctate; mid-length third of rostrum with low, almost strip-like wide median carina and 2 rows of semi-obliterated small punctures along sides; apical half shining, with sparse fine punctures. Frons feebly convex in cross-section and longitudinally. Antennae inserted at 0.46–0.47 length of rostrum from its base, club 2.56–2.84 times as long as wide. Pronotum 1.36 times as wide as long. All tibiae unarmed. First and second ventrites of abdomen rather strongly jointly convex, 2nd rather steeply sloping to 3rd ventrite. Anal ventrite feebly depressed medially at apex.

Body length 2.25–2.30 mm.

Comparison. The new species is similar to C. unguicularis , but differs in the slightly more shining, more sparsely punctate in the apical part rostrum; slightly convex and less strongly widening posteriorly, especially in anterior half, frons; less transverse pronotum with more convex disc and noticeably protruding anterior margin shallowly sinuate medially; slightly wider and more strongly narrowing posteriorly in apical half elytra with more protruding humeral prominences; narrower elytral striae and wider, flat, more densely punctate and less shining intervals; slightly wider 3rd tarsal segment and longer claw-segment; slightly longer and more widely diverging claws with finer, not fused medially and more conspicuous inner appendages. The dorsal vestiture is bicolored, so that beetles look more similar to C. typhae (Herbst, 1795) and especially to the Eastern Palaearctic C. asiaticus Korotyaev, 1997 with its long antennal club but may be immediately distinguished by the seven-segmented dark antennal funicle and appendiculate tarsal claws.

Etymology. The species is named after I. V. Melnik of Moscow, an enthusiastic amateur coleopterist, who has collected the only male of the new species and has donated to the ZIN collection this specimen together with many other interesting beetles.

Distribution. South of Transbaikalia (Zabaikalskiy Terr.) and the Russian Far East (Primorskiy Terr.), eastern Mongolia.