Adiscus variabilis ( Jacoby, 1890 )

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 : 75-77

Adiscus variabilis ( Jacoby, 1890)

(Figs 31-1; 31-2)

Dioryctus variabilis Jacoby, 1890: 114 (type locality: Chang-yang; syntype deposited: MCZ).

Adiscus variabilis: Gressitt & Kimoto, 1961: 119 (Sikang) ; Tan et al., 1980: 169; Schöller et al., 2010: 608 (catalogue).

Material examined. CHINA: Hubei Province: 1 female, Shennongjia, Mt. Guanmen [Guanmenshan], 23. VII. 1998, coll. Haisheng Zhou ( IZ-CAS) ; Sichuan Province: 1 female, Baoxing , 23. VI. 1963, coll. Leyi Zheng ; 1 female, Baoxing , 26. VI. 1963, coll. Leyi Zheng ( IZ-CAS) ; 1 female, Maowen Biological station , 30. VI. 1990, coll. Fusheng Huang ( IZ-CAS) ; 1 female, Mt. Emei [Emeishan], Jiulong Hole , 28. VI. 1957, coll. Zongyuan Wang ( IZ-CAS) ; 1 female, Wan Country, Wang’erbao , 28. V. 1994, coll. Youwei Zhang ; Yunnan Province ( IZ-CAS) : 1 female, Yongsheng, Liude , 18. VII. 1981, col. Shuyong Wang ( IZ-CAS) ; 1 female, Lushui , 11. VI. 1981, col. Shuyong Wang ( IZ-CAS) ; 1 female, Lushui , 11. VI. 1981, col. Subai Liao ( IZ-CAS) ; 1 male, Weixi, Pantiange , 24. VII. 1981, col. Shuyong Wang ( IZ-CAS) ; 1 male, Tengchong , 10. V. 1955, col. Le Wu leg ( IZ-CAS) ; 1 female, Zhenkang, Mengban , 15. V. 1955, Tianrong Huang ( IZ-CAS) ; 1 female, Dali, Mt. Cang [Cangshan], 27. VI. 2005, col. Aimin Shi ( IZ-CAS) .

Redescription. Measurements. Males. BL = 2.58–2.92 mm, BW = 1.78–2.06 mm, HL = 0.77 mm, HW = 0.82 mm, PL = 0.67 mm, PW = 1.60 mm, PA = 120°, EL = 2.20 mm, EA = 160°, Al = 0.74 mm, AW = 0.22 mm.

Females. BL = 3.00 mm, BW = 2.11 mm, HL = 0.84 mm, HW = 0.89 mm, PL = 0.73 mm, PW = 1.74 mm, PA = 120°, EL = 2.38 mm, EA = 160°, SL = 0.45 mm.

Body (Figs. 31-1A; 31-2A) small and ovate. Head fulvous, apical region partly yellow; antennomeres 1–6 fulvous, 7–11 tinged with brown, apex of mandibles black. Pronotum fulvous, basal margin black. Elytra black. Legs fulvous, claws black. Venter darkish brown.

Head round, extremely finely and sparsely punctate. Eyes reniform, slightly and broadly rounded, emarginated below middle; superior eye-lobes separated by greater distance than antennal insertions. Antennae short, reaching apical region of elytra, scape oval, its centre round, pedicel short ovate, antennomeres 3 and 4 shortest and thinnest, 6– 11 slightly broadened, each segment about equal in length, slightly longer than 5 th, last segment pointed apically.

Pronotum (Figs. 31-1A; 31-2A) convex and smooth, base much broader than apex, basal width about 2.4 times of pronotal length. Anterior margin nearly straight. Posterior margin undulated, and produced into an obtuse angle of about 120° at middle. Disc evenly convex, impunctate.

Elytra (Figs. 31-1A; 31-2A) about as broad as long, humeri slightly prominent. Disc weakly and finely punctate, with 11 indistinct regular striae, intervals without minute punctures. Epipleural lobe (Fig. 31-2B) weakly developed, lateral margins feebly expanded ventrally and nearly straight, epipleura obliquely placed and visible in lateral view.

Venter clothed with sparse short pubescence and fine punctures. Prosternum (Fig. 31-2C) trapezoidal, broader than length, lateral ridge slightly elevated, anterior margin straight. Legs thick. Pygidium with dense long pubescence.

Aedeagus. (Figs. 31-2D–F) Median lobe elongate, about 3.4 times as long as wide. Apex of median lobe slightly narrower than middle, acute at apex, moderately 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 below surface. Inner sac rather slender, cylindrical. Tegmen Y-shaped, weakly sclerotized, almost translucent.

Female. Body more robust than male, apical hollow in ventrite 5 deep and triangular. Spermatheca (Figs. 31- 1C; 31-2G) falcate, 70°-angled bending nearly halfway, slightly acute at apex, from 1/3 of apex become narrower, duct weakly sclerotized, irregularly coiled 3–4 times. Rectal sclerites (Fig. 31-1D) weakly sclerotized, closely connected between two rectangular sclerites on ventral side.

Distribution. China (Hubei, Sichuan, Yunnan, Gansu, Shaanxi); VietnamThis species is also found in Henan, Fujian and Xinjiang, China (M. Schöller, pers. com.)