Chaetocnema (Udorpes) rahlensis Shukla, 1960

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 : 186

78. Chaetocnema (Udorpes) rahlensis Shukla, 1960

Chaetocnema rahlensis Shukla, 1960: 77 . TL: India: Rahla, Upper Beas Vally. TD: Zoological Survey of India, Calcutta, India (type lost).

Distribution: India.

Host plants: Unknown.

Description (after Shukla, 1960): Body length 2.4 mm, width 1.2 mm. Body ovate, strongly convex; light bronze-colored, with cupreous reflections. labrum dark brown; first two antennal segments shiny light brown. Femora shiny bronze-colored; tibiae and tarsi lighter brown.

Head with the labrum strongly transverse, very much broader than long, angulated at the sides, anteriorly narrowed, anterior margin straight, laterally ridged; clypeus anteriorly deeply and triangularly emarginated; just behind anterior margin strongly and deeply punctate, setose; frontal tubercles and interantennal carina absent; from the middle of the interocular space two oblique, deep narrow grooves extend up to orbital border and bounded by an acute carina along the length of groove near the middle of the interocular space; vertex with fine and sparse punctures unlike the strongly punctate interocular space in front.

Eyes entire. Pronotum nearly as wide as long; the sides gently rounded, narrowing anteriorly, strongly convex; lateral margins invisible when viewed from above; rather sparsely punctate; the punctures as large as on the vertex; under higher mangification a smooth impunctate narrow longitudinal line along the middle of the disc; interstices highly granular, without depression on the disc. Scutellum short; very broad; apex acute; impunctate.

Elytral base as wide as pronotum; callus distinct but intrahumeral groove absent; very slightly depressed longitudinally behind the scutellum along the suture; punctate striate in eleven distinct rows, including a short scutellar and an extreme marginal row; the rows tend to form pairs ; in the depression behind the scutellum along the suture; the punctures irregular due to the presence of a few extra punctures in addition to those of the scutellar row; interstices granular, at the sides a few of them costate; punctures similar to the apex. Wings absent.

Underside with the gena rugosely punctate and pubescent; flanks of the pronotum with a few punctures at anterior and posterior margins; otherwise smooth and shiny; prosternum rugosely punctate; the meso- and metasterna punctate but not so deeply and closely.

Remarks: The type deposited in the Zoological Survey of India, Kolkata is lost. This species is extremely close to C. alticola , which is also apterous. However, in C. rahlensis , the pronotum is sparsely and weakly punctate, while in C. alticola , it is closely and strongly punctate.

Based on the original description, this species may be differentiated from other Oriental species by the following combination of characters: 1) frons with strong and closely placed punctures, while vertex and pronotum are rather sparsely and weakly punctate; 2) wingless, base of elytra as wide as that of pronotum; 3) pronotum nearly as wide as long, strongly convex, lateral margins invisible from above and with a longitudinal impunctate area in the middle of disc.