Adiscus crasssicornis Tan, 1992

Duan, Wen-Yuan & Zhou, Hong-Zhang, 2022, Revision of the genus Adiscus Gistel, 1857 (Coleoptera: Chrysomelidae, Cryptocephalinae) from mainland China, Zootaxa 5096 (1), pp. 1-80 : 27

Adiscus crasssicornis Tan, 1992

(Figs 10-1; 10-2)

Adiscus crasssicornis Tan, 1992b: 781 (type locality: Yunnan; type locality: IZ-CAS); Schöller et al., 2010: 608 (catalogue).

Material examined. CHINA: Holotype: male, “ Yunnan: Lushui, Pianma [ Chinese letters] / 2300 m / Chinese Academy of Sciences [ Chinese letters] // 31. V. 1981 / coll. Shuyong Wang [Chinese letters] // HOLOTYPE ”. ( IZ-CAS) ; Paratype: 1 male, “ Yunnan: Lushui, Pianma [ Chinese letters] / 2300 m / Chinese Academy of Sciences [ Chinese letters] // 26. V. 1981 / coll. Shuyong Wang [Chinese letters] // PARATYPE ”. ( IZ-CAS) ; 1 male, same as holotype, ( IZ-CAS) .

Redescription. Measurements. Males. BL = 3.21–3.56 mm, BW = 2.05–2.38 mm, HL = 0.81 mm, HW = 0.77 mm, PL = 1.17 mm, PW = 2.17 mm, PA = 80°, EL = 2.43 mm, EA= 140°, AL = 0.91 mm, AW = 0.31 mm.

Body (Figs. 10-1A; 10-2B) broad and short, subquadrate, dorsum lustrous, steel blue. Yellowish brown on clypeus, labrum and antennomeres 1–4 yellow, 7–11 black. Legs and venter mostly darkish brown, upper surface of femora, apex of femora and tarsi reddish brown.

Head shiny; finely and sparsely punctate. Eyes slightly oblong; superior eye-lobes separated by strongly greater distance than antennal insertions. Clypeus slightly prominent and declivous, anterior margin arched and emarginated apically. Vertex with a small round fovea. Antennae broad and long, reaching the middle region of the elytra, scape clubbed, pedicel cylindrical, about half as long as scape, antennomeres 3 and 4 slender, almost as long as pedicel, 5 base narrow and apex broad, 6–11 somewhat broadened and flattened, last segment pointed apically.

Pronotum (Figs. 10-1A; 10-2B) convex, smooth and shiny, base much broader than apex, basal width about twice as long as pronotal length. Anterior margin nearly straight. Posterior margin undulated, and its middle portion produced into an acute angle of about 80°. Disc evenly convex, impunctate.

Elytra (Figs. 10-1A; 10-2B) as broad as prothorax at base, humeri somewhat prominent, glabrous. Disc sparsely and finely punctate, with 11 regular striae, intervals impunctate. Epipleural lobe (Fig. 10-2B) distinct, lateral margins distinctly expanded ventrally and with arcuate lobe at basal 1/2 of elytron, with both lobe sides forming angle of 140°, epipleura obliquely placed and visible in lateral view.

Venter clothed with short pubescence. Prosternum (Fig. 10-2C) broad, trapezoidal, lateral margin slightly protruding, posterior margins weakly concave. Mesoventrite broad, width about 2.5 times as long as length, hind angles slightly protruded. Pygidium with coarse punctures and short pubescence.

Aedeagus. (Figs. 10-1C–E; 10-2D–F) Median lobe elongate, clubbed, 3 times as long as wide, apex of median lobe gradually narrower than middle and bent ventrally, acute at apex; with sparse short setae on each side of apex, impunctate. Median orifice with median sclerite bending inwards above surface. Inner sac oblate, bilobed, with two slender band. Tegmen Y-shaped, weakly sclerotized, nearly translucent.

Distribution. China (Yunnan).

Diagnosis. This species is easily distinguished from all its congeners by the long and thick antennae.