Adiscus fracticeps ( Gressitt, 1942 )

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 : 34-35

Adiscus fracticeps ( Gressitt, 1942)

(Figs 13-1)

Dioryctus fracticeps Gressitt, 1942: 333 (type locality: Lant'au I., nr. Hong Kong; type deposited: ICRI).

Adiscus fracticeps: Gressitt & Kimoto, 1961: 117 ; Schöller et al., 2010: 607 (catalogue).

Material examined. CHINA: Holotype: male, “ Tung-chung , Lan-t’au Island, near Hong Kong // 7. VIII. 1934 / coll. Y. W. Djou // HOLOTYPE ”. ( ICRI).

Redescription. Measurements. Male. BL = 3.30 mm, BW = 2.45 mm, HL = 0.92 mm, HW = 0.99 mm, PL = 1.03 mm, PW = 2.24 mm, PA = 130°, EL = 2.48 mm, EA = 110°.

Body (Fig. 13-1A) fairly broad; rounded oblong, mostly reddish ochraceous. Labrum and mandibles pitchy to black. Antennae ochraceous on first three and a half segments, remainder pitchy black. Pronotum with basal margin black. Elytra with anterior margin black. Metaventrite with sides slightly pitchy. Venter brown ochraceous.

Head round, with close punctures on frons and sparse punctures on occiput. Eyes reniform; superior eye-lobes separated by slightly greater distance than antennal insertions, with a short longitudinal groove between upper ends of eyes. Clypeus with anterior margin slightly arched and emarginated. Antennae, reaching beyond humeral region of the elytra, scape clubbed and long, pedicel subspherical, about 1/2 as long as the scape, antennomeres 3–4 minute, nearly as long as pedicel, 5–11 somewhat broadened and flattened, last segment pointed apically.

Pronotum (Fig. 13-1A) convex, smooth and shiny, strongly narrowed anteriorly, basal width about twice of pronotal length. Anterior margin nearly straight. Posterior margin sinuate with fine serration, and produced into an obtuse angle of about 130° at middle. Disc evenly convex, impunctate.

Elytra (Fig. 13-1A) with humeri prominent and glabrous, slightly narrowed behind humerus, slightly rounded apically. Disc distinctly punctate, with 11 regular striae, with shallow minute punctures between rows. Epipleural lobe large, lateral margins distinctly expanded ventrally with rounded lobe at basal 1/2 of elytron, with both lobe sides forming angle of 110°, epipleura obliquely placed and indistinct in lateral view.

Venter clothed with short pubescence and fine punctures. Prosternum trapezoidal, lateral margin broad and convex, lateral ridges elevated, anterior margin not protruding, posterior margin nearly straight, central ridge absent. Mesoventrite rectangular, twice as wide as long, lateral ridges elevated. Metaventrite with irregular fine punctures. Pygidium with dense punctures and short pubescence.

Distribution. China (Guangdong).

Diagnosis. Allied to A. mouhoti , but can be distinguished by smaller size and darker ochraceous coloration, the pronotum nearly impunctate, the sublateral puncture-row of elytra distinctly grooved.