Adiscus annulatus (Pic, 1922)

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 : 15-18

Adiscus annulatus (Pic, 1922)

(Figs. 5-1; 5-2)

Dioryctus annulatus Pic, 1922a: 14 (type locality: Yunnan; type deposited: MNHN);

Adiscus annulatus: Gressitt & Kimoto, 1961: 116 (Fukien, Kwangtung) ; Schöller et al., 2010: 607 (catalogue).

= Dioryctus alternatus Chen, 1941: 190 (type locality: Yaoshan; type deposited: IZ-CAS);

= Adiscus alternatus: Gressitt & Kimoto, 1961: 116 (as synonym of Adiscus annulatus ).

Material examined. CHINA: Holotype Dioryctus alternatus Chen : female, “ Guangxi: Xiuren, Yaoshan [ Chinese letters] / Chinese Academy of Sciences [Chinese letters] // 1938 // HOLOTYPE ”. ( IZ-CAS) ; Additional material: Yunnan Province: 1 male, Xishuangbanna, Mengzhe , 11. VII. 1958, coll. Shuyong Wang ( IZ-CAS) ; 1 female, Xishuangbanna, Mengla , 24. V. 1959, coll. Fuji Pu ( IZ-CAS) ; 1 female, Simao, Laojiezi , 22. V. 1957, coll. Zenghao Zhu ( IZ-CAS) .

Redescription. Measurements. Males. BL = 2.59–2.81 mm, BW = 1.68–1.82 mm, HL = 1.00 mm, HW = 0.95 mm, PL = 1.84 mm, PW = 0.88 mm, PA = 100°, EL = 2.15 mm, EA = 130°, AL = 1.03 mm, AW = 0.33 mm.

Females. BL = 2.88–3.12 mm, BW = 1.82–1.94 mm, HL = 1.08 mm, HW = 1.03 mm, PL = 2.00 mm, PW = 0.96 mm, PA = 100°, EL = 2.33 mm, EA = 130°, SL = 0.71 mm.

Body (Figs. 5-1A; 5-2A) short and ovate, subrounded. Head darkish red; antennae yellowish brown, apex of mandibles black; frons in between eyes piceous. Pronotum darkish red, basal margin narrowly black. Elytra black with a transverse darkish red marking, covering 2/3 area of elytra and extending from the suture to 10 th puncture row. Venter reddish brown.

Head dull, densely and coarsely punctate. Eyes reniform, superior eye-lobes separated by slightly greater distance than antennal insertions. Clypeus semicircular, with sparsely fine punctures, and anterior margin weakly emarginated. Antennae short, reaching about basal 1/4 of elytra; scape clubbed, pedicel short, about 1/3 as long as scape, antennomeres 3 and 4minute, pedicel rarely longer than 3or 4, 5 slightly broadened apically, 6–11 somewhat broadened and flattened, last segment pointed apically.

Pronotum (Figs. 5-1A; 5-2A) strongly convex, base much broader than apex, basal width about twice pronotal length. Anterior margin weakly convex. Lateral margins nearly straight. Posterior margin slightly sinuate with fine serration, and produced into an obtuse angle of about 100° at middle. Disc evenly convex, with fine and rather close punctures, smaller than those on head.

Elytra (Figs. 5-1A; 5-2A) as broad as prothorax at base, humeri weakly prominent, glabrous. Disc finely punctate, with 11 regular striae, intervals with scattered minute punctures, puncture striae irregular on apical slope. Epipleural lobe (Fig. 5-2B) distinct, lateral margins distinctly expanded ventrally with rounded lobe at basal 1/4 of elytron, with both lobe sides forming an angle of 130°, epipleura obliquely placed and visible in lateral view.

Venter clothed with short pubescence and dense punctures. Prosternum (Fig. 5-2C) trapezoidal, lateral margin broad and convex strongly, weakly arcuate in lateral view; central ridge weakly elevated, anterior margin not protruding, posterior margin nearly straight. Mesoventrite length shorter than half of prosternum, width about 3.3 times of length. Metaventrite with dense and coarse punctures. Pygidium with dense punctures and short pubescence.

Aedeagus. (Figs. 5-1E–G; 5-2D–F) Median lobe elongate, 3.1 times as long as wide, parallel-sided, apex of median lobe gradually narrow and rounded, bent ventrally and curved in lateral view, with feeble dense punctures on ventral side of distal part, without setae. Median orifice with median sclerite bending inwards beyond surface. Inner sac slender, cylindrical, contracted on basal third, slightly narrow at apex. Tegmen, Y-shaped, weakly sclerotized, nearly translucent.

Female. Body more robust than male, apical hollow in ventrite 5 shallow and round. Spermatheca (Figs. 5- 1C; 5-2G) falcate, 60°-angled bending halfway, acute at apex; duct base thickened strongly, coiled, then becoming thinner, and coiled about 4–5 times. Rectal sclerites (Fig. 5-1D) strongly scerotized, two sclerites rectangular, not connected in ventral view.

Distribution. China (Fujian, Guangdong, Guangxi, Yunnan).