Chaetocnema (Chaetocnema) cheni Ruan, Konstantinov & Yang, 2014

Ruan, Yongying, Yang, Xingke, Konstantinov, Alexander S., Prathapan, Kaniyarikkal D. & Zhang, Mengna, 2019, Revision of the Oriental Chaetocnema species (Coleoptera, Chrysomelidae, Galerucinae, Alticini), Zootaxa 4699 (1), pp. 1-206 : 31-33

4. Chaetocnema (Chaetocnema) cheni Ruan, Konstantinov & Yang, 2014

( Figs. 19 , 20 )

Chaetocnema (Chaetocnema) cheni Ruan, Konstantinov and Yang, 2014: 21 . TL: China, Yunnan. TD: IZCAS.

Distribution: China (Jiangxi, Hunan, Sichuan, Yunnan).

Host plants: Solanum tuberosum .

Description: Male body length: 1.85–2.05 mm, excluding head: 1.79–1.93 mm. Male body width: 1.00–1.05. Female body length: 2.10± 0.1 mm. Ratio of length of antenna to length of body: 0.60–0.62. Ratio of elytron length (along suture) to width (maximum) 2.50–2.60. Ratio of pronotum width (at base) to length: 1.46±0.05. Ratio of length of elytron to length of pronotum (along middle): 2.90±0.05. Ratio of width of elytra at base to width of pronotum at base (in middle of humeral calli): 1.16±0.05. Ratio of maximum width of elytra to that of pronotum: 1.53±0.05.

Elytra concolorous with pronotum or slightly different. Elytra coppery, sometimes blue black. Color of pronotum coppery, sometimes bronzy. Head dorsally coppery, sometimes bluish black. Antennomere 1 partially dark brown, 2–3 yellow, 4–5 partially brown, rest black. Pro- and mesofemora brown with yellow apex. Metafemora brown. Tarsi brown with yellow on base of each tarsomere.

Head hypognathous. Frontal ridge between antennal sockets narrow, convex. Frontolateral sulcus present. Suprafrontal sulcus shallow and faint or deep laterally, shallow in middle. Suprafrontal sulcus retuse. Orbital sulcus (above antennal socket) deep. Ratio of width of frontal ridge to width of antennal socket: 1.19±0.05. Ratio of width of orbital sulcus (above antennal socket) to width of frontolateral sulcus: 0.64–0.66. Surface of vertex sparsely and unevenly covered with 6–7 punctures close to each eye. Number of punctures on orbit on each side: 1. Number of setae along frontolateral sulcus on each side: 9–10. Frons (triangular area surrounded by frontolateral sulcus and clypeus) without punctures. Number of setae on clypeus: 7. Number of setae on labrum: 6. Anterior margin of labrum slightly concave in middle.

Pronotum with two short, obscure longitudinal impressions near basal margin. Longitudinal impressions lack punctures. Deep row of large punctures at base of pronotum present laterally, absent in middle. Shape of pronotal base evenly convex. Anterolateral prothoracic callosity protruding laterally, poorly developed. Posterolateral prothoracic callosity projects up to lateral margin of pronotum. Diameter of pronotal punctures 2 to 4 times smaller than distance between them.

Elytra with convex sides. All rows of punctures on elytra regular. Elytral humeral calli well developed. Interspaces of puncture rows smooth and glabrous. Number of minute puncture rows on each interspace: 2.

First male protarsomere distinctly larger than second. First male protarsomere, length to width ratio: 1.50±0.05. First and second male protarsomeres, length to length ratio: 1.68±0.05, width to width ratio: 1.23±0.05. Ratio of first male protarsomere, width at apex to width at base: 1.87–2.00. Length of metatibia to distance between denticle and metatibial apex: 2.34–2.47. Large lateral denticle on metatibia sharp. Metatibial serration proximal to large lateral denticle obtuse. Metatibia proximad to denticle convex in dorsal view. First male metatarsomere, length to width ratio: 2.47–2.68. First and second male metatarsomeres, length to length ratio: 1.58–1.62; width to width ratio: 0.92–1.00. Third and fourth male metatarsomeres, length to length ratio: 0.71±0.05. Metatibia length to the metafemora length: 0.75±0.05.

Aedeagus gradually widening towards apex. Apex of aedeagus in ventral view narrowing abruptly forming a subtriangular apex. Ventral surface of aedeagus lateral to median groove apically convex. Ventral longitudinal groove shallow basally, not extending to middle or apex. Apical denticle of aedeagus in ventral view absent. Apex of aedeagus in lateral view slightly curved ventrally. Minute transverse wrinkles on ventral side of aedeagus absent. Aedeagus in lateral view slightly sinusoidal near apex. Aedeagus narrow in lateral view. Maximum curvature of aedeagus in lateral view situated medially. Ratio of width (in middle) to length of aedeagus (in ventral view) about: 0.14.

Spermathecal receptacle barrel-shaped. Basal part of spermathecal duct straight. Spermathecal pump much shorter than receptacle, with cylindrical apex. Receptacle basally wider than apically, with maximum width situated medially. Posterior sclerotization of tignum spoon-shaped, wider than mid-section. Anterior sclerotization of tignum wider than mid-section. Apex of vaginal palpus subtriangular, with lateral margin slightly convex. Sides of mid part of vaginal palpus (before apex) narrowing from base, slightly widening towards apex. Anterior sclerotization of vaginal palpus slightly widening anteriorly, slightly and evenly curved along length. Anterior end of anterior sclerotization nearly rectangular. Posterior sclerotization longer than wide. Posterior sclerotization wider than anterior.

Types (in IZCAS): 1♂ (Holotype), Longling, Yunnan ( China), alt. 1600m, 1955.V.20, leg. В. Попов (B. Pop- ov); 2♀ 1♂ (Paratypes), Tianping Mountain , Sangzhi, Hunan ( China), alt. 1370, 1988.VIII.15, leg. Shuyong Wang ; 3♀ 1♂ (Paratypes), Jiujiang , Jiangxi ( China), 1958.VII–VIII ; 2♀ (Paratypes), Jiujiang , Jiangxi ( China), 1948.VII ; 2♀ 4♂ (Paratypes), Jinfou Mountain , Sichuan ( China), 1945.VIII.16. leg. Shuyong Wang ; 20 (Paratypes), Liziping , Wushan, Sichuan ( China), alt. 1850m, 1993.V.18–19, leg. Youwei Zhang ; 4♂ 5♀ (Paratypes), Liziping , Wushan, Si- chuan ( China), alt. 1850m, 1993.VIII.5–6, leg. Xingke Yang , feed on Solanum tuberosum Linn. ; 1♂ (Paratypes), Jinpinghe , Yunnan ( China), alt. 1700m, 1956.V.14, leg. Keren Huang.

Remarks: Color vary significanty among the specimens examined. The holotype (from Longling, Yunnan) is copper colored, while the paratypes from Jinfou Mountain, Sichuan have greenish-bronze pronotum and blue-black elytra.

Chaetocnema cheni may be differentiated from C. kingpinensis and C. constricta by the following characters: first male protarsomere obviously larger than the second, appendages darker in color, anterolateral angles of pronotum round. Chaetocnema cheni may be differentiated from C. picipes and C. granulosa based on the following characters: metatibia proximad to denticle in dorsal view convex, apex of aedeagus is subtriangular and broad.

Figures

FIGURE 19. Chaetocnema cheni. A Holotype, habitus. B Prothorax. C Head. D Aedeagus, ventral and lateral views. E Apex of Aedeagus, dorsal view. F Vaginal palpi. G Spermatheca. H Tignum.

FIGURE 20. Chaetocnema cheni. A–B Habitus, indicating variation in color. C Ventral view of body. D Lateral view of body.