Adiscus exilis ( Weise, 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 : 32-34

Adiscus exilis ( Weise, 1922)

(Figs 12-1; 12-2)

Dioryctus exilis Weise, 1922: 43 (type locality: Yunnan; type deposited: NHRS); Gressitt, 1942: 332.

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

Material examined. CHINA: Sichuan Province: 1 female, Luding, Moxi , 13. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; 1 female, Luding, Moxi, Hailuogou , 16. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; 1 female, Luding, Xinxing, Yanzigou , 17. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; Yunnan Province: 21 males, 17 females, Weixi Pantiange , 2750 m, 22. VII. 1981, coll. Shuyong Wang ( IZ-CAS) ; 3 females, Weixi Pantiange , 2500 m, 25. VII. 1981, coll. Shuyong Wang ( IZ-CAS) ; 2 females, Weixi Pantiange , 2400 m, 25. VII. 1981, coll. Shuyong Wang ; 1 female, Weixi Baijixun , 1780 m, 10. VII. 1981, coll. Shuyong Wang ( IZ-CAS) ; 1 female, Xishuangbanna Mengzhe , 15. VI. 1958, coll. unknown ( IZ-CAS) ; 1 female, Xishuangbanna Mengzhe , 25. VI. 1958, coll. Shuyong Wang ( IZ-CAS) ; 1 female, Kunming , time unknown, coll. unknow ( IZ-CAS) ; Tibet: 1 male, Motuo, Gedang , 23. IX. 1982, coll. Yanheng Han ( IZ-CAS) .

Redescription. Measurements. Males. BL = 1.86–2.12 mm, BW = 1.28–1.58 mm, HL = 0.76 mm, HW = 0.74 mm, PL = 0.49 mm, PW = 1.16 mm, PA = 80°, EL = 1.58 mm, EA = 120°, AL = 0.69 mm, AW = 0.25 mm.

Females. BL = 2.03–2.49 mm, BW = 1.46–1.62 mm, HL = 0.83 mm, HW = 0.81 mm, PL = 0.54 mm, PW = 1.26 mm, PA = 80°, EL = 1.72 mm, EA = 120°, SL = 0.40 mm.

Body (Figs. 12-1A; 12-2A) small, ovate; head mostly black, clypeus light brown; labrum and antennomeres 1–4 yellowish brown, 5–11 darkish brown. Pronotum reddish brown, and posterior margin black. Elytra reddish brown, basal margin black. Abdomen black, propleura yellowish brown, apex of last segment of abdomen and pygidium yellowish brown; legs yellowish brown, apex of femur and tibia slightly black, claws black.

Head dull; coarsely punctate. Eyes reniform; superior eye-lobes almost equally separated as antennal insertions. Clypeus densely granulose and sparsely punctate, anterior margin slightly arched and emarginated apically. Frons with sparse punctures and sparse short hairs, and intervals scattered with minute punctures.Antennae short, reaching elytral humeri, scape clubbed, pedicel elliptic, about half as long as scape, antennomeres 3 and 4 short and slender, both slightly shorter than pedicel, 5 subtriangular, base narrow and apex broad, 6–11 somewhat broadened and flattened, each segment longer than those of basal, last segment pointed apically.

Pronotum (Figs. 12-1A; 12-2A) convex, much broader basely than apically, basal width about 2.3 times as long as pronotal length. Anterior margin nearly straight. Posterior margin slightly sinuate with fine serration, and produced into an acuteangle of about 80° at middle. Disc convex, finely and rather evenly punctate.

Elytra (Figs. 12-1A; 12-2A) as broad as long, humeri somewhat prominent, glabrous. Disc sparsely and finely punctate, with 11 regular striae, intervals sparsely and finely punctate. Epipleural lobe (Fig. 12-2B) large, lateral margins distinctly expanded ventrally with rounded lobe at basal 1/2 of elytron, with both lobe sides forming angle of 120°, epipleura obliquely placed and visible in lateral view.

Venter clothed with fine punctures and short pubescence. Prosternal episternum slightly rugose. Prosternum (Fig. 12-2C) trapezoidal, lateral margin protruded strongly, anterior margin slightly arched emarginated, posterior margin nearly straight, lateral ridges elevated, straight in lateral view. Mesoventrite broad, twice as wide as long, with dense coarse punctures. Pygidium with coarse dense punctures.

Aedeagus. (Figs. 12-1D–F; 12-2D–F) Median lobe elongate, about 2.7 times as long as wide, nearly parallelsided. Apex of median lobe slightly narrower than middle, acute at apex, strongly curved in lateral view; with several short setae on each side of apex, densely punctate on ventral side of distal part. Median orifice with median sclerite bending inwards above surface. Inner sac rather oblong, cylindrical. Tegmen Y-shaped, weakly sclerotized, almost translucent.

Female. Body more robust than male, apical hollow in ventrite 5 shallow and round. Spermatheca (Figs. 12- 1C; 12-2G) falcate, right-angled bending from apex 3/5, acute at apex, become narrower from apex 1/5; duct weakly sclerotized, irregularly coiling 4–6 times. Rectal sclerites (Fig. 12-1G) moderately sclerotized, not connected between two rectangular sclerites on ventral side.

Distribution. China (Guangdong, Sichuan, Guizhou, Yunnan, Xizang).