Adiscus humeralis (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 : 40-41

Adiscus humeralis (Pic, 1922)

(Figs 16-1; 16-2)

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

Adiscus humeralis: Gressitt & Kimoto, 1961: 117 (Hupeh) ; Kimoto & Gressitt, 1981: 325 ( Tonkin); Schöller et al., 2010: 607 (catalogue).

= Dioryctus auricacumen Gressitt, 1942: 331 (type locality: Mt. Omei ; type deposited: ICRI).

= Adiscus auricacumen: Gressitt & Kimoto, 1961: 117 (as synonym of A. humeralis ).

Material examined. CHINA: Sichuan Province: 7 males, 8 females, Luding, Moxi, Hailuogou , 1550 m, 16. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; 7 males, 4 females, Luding, Moxi, Hailuogou , 1550 m, 18. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; 1 female, Luding, Moxi, Hailuogou , 1550 m, 13. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; 1 female, 1 male, Luding, Moxi, Hailuogou , 1550 m, 14. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; 22 males, 18 females, Luding, Moxi, Hailuogou , 1550 m, 17. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; 8 males, 7 females, Luding, Moxi, Hailuogou , 1550 m, 17. IX. 1982, coll. Yuanqing Chen ( IZ-CAS) ; 2 males, Luding, Moxi, Hailuogou , 1600 m, 18. VI. 1983, coll. Shuyong Wang ( IZ-CAS) ; 2 males, Luding, Moxi, Hailuogou , 1600 m, 18. VI. 1983, coll. Yuanqing Chen ( IZ-CAS) ; 2 females, Luding, Moxi, Hailuogou , 1600 m, 18. VI. 1983, coll. Xuezhong Zhang ( IZ-CAS) ; 2 males, 5 females, Luding, Moxi, Hailuogou , 1500 m, 20. VI. 1982, coll. Xuezhong Zhang ( IZ-CAS) ; 1 male, 4 females, Luding, Moxi, Hailuogou , 1650 m, 20. VI. 1983, coll. Shuyong Wang ( IZ-CAS) ; 1 female, 1 male, Luding, Xinxing , 1900 m, 13. VI. 1983, coll. Yuanqing Chen ( IZ-CAS) ; 1 female, Luding, Xinxing, Yanzigou 2000 m, 17. IX. 1982, coll. Shuyong Wang ( IZ-CAS) ; 1 female, Luding, Xinxing, Dewei , 1230 m, 21. VI. 1983, coll. Shuyong Wang ( IZ-CAS) ; Yunnan Province: 1 female, 1 male, Kongming, Mt. Western , 2000 m, 7. VII. 1956, coll. Keren Huang ( IZ-CAS) .

Redescription. Measurements. Males. BL = 2.53–2.94 mm, BW = 2.00– 2.34 mm, HL = 1.29 mm, HW = 0.98 mm, PL = 0.89 mm, PW = 1.88 mm, PA = 70°, EL = 2.11 mm, EA = 140°, AL = 1.25 mm, AW = 0.45 mm.

Females. BL = 2.79–3.23 mm, BW = 2.13–2.34 mm, HL = 1.40 mm, HW = 1.07 mm, PL = 0.89 mm, PW = 1.88 mm, PA = 70°, EL = 2.11 mm, EA = 140°, SL = 0.43 mm.

Body (Figs. 16-1A; 16-2A) medium sized, oblong; dorsum shiny. Head yellowish brown, sometimes vertex black; mandibles reddish brown, apex black; labrum, ventral side of mouth parts and antennomeres 1–5 yellow, 6–11 brown or dark brown. Basic color of pronotum yellowish brown or reddish brown, lateral middle margin and posterior margin black. The most common variety with a narrow transverse black stripe along basal margin of elytra, and a large black spot at humeral region, sometimes extending downward, rarer variety with elytra almost black. Legs yellowish brown, except claws black. Venter yellowish brown, lateral ridge of prosternum black, pygidium yellowish brown.

Head dull, coarsely punctate and with short pubescent. Eyes distinct, reniform; superior eye-lobes separated by moderately greater distance than antennal insertions. The interspace of antennal sockets semicircular emarginated, as a boundary between frons and clypeus. Clypeus densely granulose and sparsely punctate, anterior margin arched and emarginated apically. Frons with coarse punctures, scattered with minute punctures. Antennae short, reaching the humeral region of the elytra, scape clubbed, swollen, pedicel oblong, about 1/3 as long as scape, antennomeres 3 and 4 slender, pedicel as long as 3, 5 subtriangular, about as long as 4, 6–11 somewhat broadened and flattened, 6–10 about equal in length, last segment pointed apically.

Pronotum (Figs. 16-1A; 16-2A) convex, much broader basely than apically, basal width about 2.1 times as long as pronotal length. Anterior margin nearly straight. Posterior margin sinuate with fine serration, and produced into an acute angle of about 70° at middle. Disc evenly convex, finely and rather sparsely punctures, and scattered with strongly fine punctures.

Elytra (Figs. 16-1A; 16-2A) as broad as long, humeri somewhat prominent. Disc finely punctate lateral two puncture rows and base with distinct punctures, with 11 regular striae, strial intervals with scattered minute and fine punctures. Epipleural lobe (Fig. 16-2B) large, lateral margins distinctly expanded ventrally with rounded lobe at basal 1/2 of elytra, with both lobe sides forming angle of 140°, epipleura not visible in lateral view.

Venter clothed with short pubescence and fine punctures. Prosternum (Fig. 16-2C) trapezoidal, with dense coarse punctures, anterior margin finely rugose and arcuately concave, lateral margin elevated to a ridge. Mesoventrite densely and coarsely punctate, twice as wide as long Pygidium with dense coarse punctures.

Aedeagus. (Figs. 16-1D–F; 16-2D–F) Median lobe elongate, about 3 times as long as wide, distinctly narrow at base 1/3. Apex of median lobe moderately narrower than middle, strongly acute at apex, slightly curved in lateral view; with several 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 slender, cylindrical, basal margin nearly round. Tegmen Y-shaped, weakly sclerotized, almost translucent.

Female. Body more robust than male, apical hollow in ventrite 5 shallow and round. Spermatheca (Figs. 16-1C; 16-2G) falcate, right-angled bending halfway, acute at apex, become narrower from apex 1/3; duct weakly sclerotized, irregularly coiled. Rectal sclerites (Fig. 16-1G) strongly sclerotized, not connected between two rectangular sclerites on ventral side.

Distribution. China (Hubei, Sichuan, Yunnan); Vietnam.