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We dedicate this species to SH Chen, who originally designated it as new, but left it unpublished. Professor Chen was a classic Chinese entomologist, he laid the foundation for studies of leaf beetles in China.
Hunan, Jiangxi, Sichuan, Yunnan.
Chaetocnema cheni sp. n. can be differentiated from Chaetocnema kingpinensis sp. n. and Chaetocnema constricta sp. n. by the following characters: first male protarsomere clearly larger than second, appendages darker in color, anterolateral angles of pronotum round. Chaetocnema cheni can be differentiated from Chaetocnema picipes and Chaetocnema fortecostata based on the following characters: metatibia proximad to denticle in dorsal view convex, apex of aedeagus subdeltoid, tip of aedeagus widely rounded.
MBL = 1.85–2.05 mm; MBH = 1.79–1.93 mm; FBL = 2.10±0.05 mm; FBH = 2.05±0.05 mm; AL/BL = 0.60–0.61; MBW = 1.04–1.06; EL/EW = 1.29; PW/PL =1.47±0.05; EL/PL = 2.91±0.05; EWB/PWB = 1.17±0.05; EWM/PWM = 1.53±0.05.
Color of elytra usually same with or slightly different from pronotum. Color of elytra copperish, sometimes bluish black. Color of pronotum copperish, sometimes bronzish. Head dorsally copperish, sometimes bluish black. Antennomere 1 partly dark brown. Antennomeres 2–3 yellow. Antennomeres 4–5 partly brown. Remaining antennomeres 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 and convex. Frontolateral sulcus present. Suprafrontal sulcus shallow and faint or deep laterally, shallow in middle. Suprafrontal sulcus slightly concave. Orbital sulcus (above antennal socket) deep. Width of frontal ridge to width of antennal socket: 1.19±0.05. Width of orbital sulcus (above antennal socket) to width of frontolateral sulcus: 0.64–0.67. Surface of vertex sparsely and unevenly covered with 6–7 punctures close to each eye. Numbers of punctures on orbit on each side: 1. Numbers of setae along frontolateral sulcus on each side: 9–10. Numbers of setae on frons (triangular area surrounded by frontolateral sulcus and clypeus): 0. Numbers of setae on clypeus: 7. Numbers of setae on labrum: 6. Anterior margin of labrum slightly concave in middle.
Base of pronotum with two short, obscure longitudinal impressions near basal margin. Longitudinal impressions lack punctures. Deep row of large punctures at base of pronotum present on sides, lacking in middle. Shape of pronotal base evenly convex. Anterolateral prothoracic callosity protruding laterally but 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 elytron regular and single. Elytral humeral calli well developed. Interspaces of puncture rows smooth and glabrous. Numbers of minute punctures lines 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: 1.69±0.05, width to width ratio: 1.23±0.05. 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 present, obtuse. Metatibia proximad to denticle in dorsal view convex. First male metatarsomere, length to width ratio: 2.47–2.68. First and second male metatarsomeres, length to length ratio: 1.58–1.62. First and second male metatarsomeres, 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: 0.76±0.05.
Median lobe of aedeagus widening gradually towards apex. Apical part of median lobe in ventral view narrowing abruptly forming a subdeltoid apex. Ventral surface of median lobe lateral to median groove apically convex. Ventral longitudinal groove absent in apical and middle part, shallow in basal. Apical denticle of aedeagus in ventral view absent. Apical part of aedeagus in lateral view slightly curved ventrally. Minute transverse wrinkles on ventral side of median lobe absent. Median lobe in lateral view slightly sinusoidal near apex. Median lobe narrow in lateral view. Maximal curvature of median lobe in lateral view situated medially. Width (in middle) to length of median lobe (in ventral view) about: 0.14.
Spermathecal receptacle pear-shaped. Spermathecal pump much shorter than receptacle. Apex of spermathecal pump cylindrical. Spermathecal pump attached to middle of receptacle top. Maximum width of receptacle situated basally. Basal part of receptacle wider than apical. Posterior sclerotization of tignum spoon-shaped, wider than mid section. Anterior sclerotization of tignum wider than mid section. Apex of vaginal palpus subdeltoid, with lateral side slightly arching. 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 flat. Length of posterior sclerotization greater than width. Width of posterior sclerotization greater to anterior sclerotization.
(all the materials preserved in IZCAS): Holotype: 1♂ (Fig. 3: A), Longling, Yunnan, alt.1600m, 1955.V.20, leg. В. Попов (B. Popov). Paratypes: 2♀1♂, Tianping Mountain, Sangzhi, Hunan, alt.1370, 1988.VIII.15, leg. Shuyong Wang; 3♀1♂, Jiujiang, Jiangxi, 1958.VII-VIII; 2♀, Jiujiang, Jiangxi, 1948.VII; 2♀4♂, Jinfou Mountain, Sichuang, 1945.VIII.16. leg. Shuyong Wang; 20, Liziping, Wushan, Sichuan, alt.1850m, 1993.V.18-19, leg. Youwei Zhang; 4♂5♀, Liziping, Wushan, Sichuan, alt.1850m, 1993.VIII.5-6, leg. Xingke Yang, feed on Solanum tuberosum Linn.; 1♂, Jinpinghe, Yunnan, alt.1700m, 1956V.14, leg. Keren Huang.
There is a noticeable variability in body color among studied specimens. The holotype collected from Longling, Yunnan province is copperish in color, but the paratypes from Jinfou Mountain, Sichuang Province have greenish-bronzish pronotum and blue-blackish elytra.
- Ruan, Y; Konstantinov, A; Ge, S; Yang, X; 2014: Revision of the Chaetocnema picipes species-group (Coleoptera, Chrysomelidae, Galerucinae, Alticini) in China, with descriptions of three new species ZooKeys, 387: 11-32. doi