Chaetocnema (Chaetocnema) yonyonae Chen, 1934

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 : 123

49. Chaetocnema (Chaetocnema) yonyonae Chen, 1934

Chaetocnema yonyonae Chen, 1934: 246 . TL: Vietnam ( Tonkin). TD: MNHN.

Distribution: Vietnam ( Tonkin).

Host plants: Unknown.

Description (after Chen 1934): Body length 2.5 mm. Antennae stout, pronotum with posterior angle rounded, somewhat produced. Body ovate, rather strongly narrowed behind. Shining metallic blue, with the pronotum slightly green; four basal antennomeres and legs dark red-brown; apical antennomeres piceous; posterior femora metallic.

Head finely granulose, very sparsely and finely punctate, with frontal transverse depression very shallow and clypeus with a few setae on each side. Antennae reach a little beyond humeral calli, second antennomere thicker but not shorter than the third or fourth, each of the following antennomeres slightly longer than fourth and thicker than most other species of the genus. Pronotum finely and very closely reticulate, covered with moderately strong but fairly close punctation, basal transverse row of punctures absent; lateral margins converging in front; posterior angles rounded, somewhat produced. Scutellum semi-circular, impunctate. Elytra rather strongly punctate, punctures very regularly arranged; interstices distinctly and closely punctate, lateral ones subcostate.

Remarks: We could not locate the type in MNHN. Based on the original description, this species closely resembles C. yunnanica in almost all aspects. However, in C. yonyonae , the vertex is punctate in the middle and not raised (in C. yunnanica , vertex is impunctate in the middle and distinctly raised). This species can be separated from its other Oriental congeners by the strongly narrowed hind part of the body and the strongly and very closely punctate elytral interspaces ( Chen, 1934).