Chaetocnema (Udorpes) angustifrons Ruan, Konstantinov & Yang, 2019

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 : 133-135

54. Chaetocnema (Udorpes) angustifrons Ruan, Konstantinov & Yang , New Species

( Fig. 76 )

Etymology: This species is named after its narrow frons and interocular space. Specific epithet is a noun in apposition.

Diagnosis: This unique species can be distinguished from other Oriental Chaetocnema species by combination of the following characters: pronotum almost quadrate with straight and parallel sides, head and frons narrow (distance between eyes only slightly larger than diameter of one eye), first tarsomere of male long and narrow.

Distribution: Thailand, Cambodia.

Host plants: Unknown.

Description: Body length: 2.10–2.35 mm. Body width: 1.15–1.25 mm. Ratio of length of antenna to length of body: 0.68–0.70. Ratio of elytron length (along suture) to width (maximum): 2.30–2.35. Ratio of pronotum width (at base) to length: 1.60–1.62. Ratio of length of elytron to length of pronotum (along middle): 2.60–2.61. Ratio of width of elytra at base (in middle of humeral calli) to width of pronotum at base: 1.12–1.14.

Dorsum bronzy. Antennomeres completely yellow brown, with apical five darkened. Tarsi, tibiae, pro- and mesofemora yellow brown. Metafemora dark brown, sometimes with very slight bronzy luster.

Head hypognathous. Frontal ridge not wide, flat. Frons and frontal ridge covered with large and closely placed punctures and white setae. Ratio of width of frontal ridge to width of antennal socket: 1.70–1.75. Frontolateral sulcus absent. Suprafrontal sulcus obsolete, obcordate, with a pit in middle. Orbital, supraantennal sulci poorly developed. Vertex flat, situated on same level as orbit. Vertex evenly covered with punctures, with an impunctate longitudinal area in middle. Punctures on frons larger than those on vertex.

Base of pronotum without short longitudinal impressions. Pronotal base evenly convex. Deep transverse row of large punctures along base of pronotum absent. Punctures absent on narrow transverse area adjacent to midbasal margin of pronotum. Anterolateral prothoracic callosity moderately developed, truncate and oblique. Lateral margins of pronotum almost straight, parallel. Posterolateral prothoracic callosity poorly developed. Diameter of pronotal punctures 1.5–3 times smaller than distance between them.

Humeral callus well-developed. Elytra with convex lateral sides. Scutellar row of elytral punctures paired and confused. Second to eleventh rows of elytral punctures regular. Elytral interspaces between puncture rows almost flat at sides.

First protarsomere comparatively long and narrow in male. Excavation on metatibia not deep. Large lateral denticle on metatibia obtuse. Metatibial serration proximal to large lateral denticle absent.

In ventral view, aedeagus parallel-sided, apex narrowing gradually. Ventral longitudinal groove of aedeagus well developed, minute, transverse wrinkles present throughout. Ventral longitudinal ridge in middle of aedeagus absent. Apical denticle of aedeagus present in ventral view, truncate apically. Aedeagus in lateral view curved at base, straight at apex.

Receptacle of spermatheca sinuated. Spermathecal pump much shorter than receptacle, with apex flattened. Maximum width of receptacle situated near apex. Receptacle basally narrower than apically. Vaginal palpus slightly narrowing from base till middle, thence approximately parallel sided. Anterior sclerotization of vaginal palpus slightly widening anteriorly. Posterior sclerotization longer than wide. Anterior sclerotization wider than posterior.

Types: Holotype: ♂ ( USNM), labels: 1) Thailand, Korat. Si Khiu, Pak Chong , 23.VIII.1952; 2 ) Holotype, Chaetocnema angustifrons sp. nov., Des. Ruan, 2016.

Paratypes: 3♂ 3♀ ( USNM), Thailand, Korat. Si Khiu, Pak Chong , 23.VIII.1952 , Paratype, Chaetocnema angustifrons sp. nov., Des. Ruan, 2016; 2♀ ( USNM), Thailand, Lop Buri Airawan Mt. , 9.VII.1953, R. E. Elbel , Paratype, Chaetocnema angustifrons sp. nov., Des. Ruan, 2016; 1♀ ( USNM), Cambodia, Siem Reap, XI.1958, NLH Krauss , Paratype, Chaetocnema angustifrons sp. nov., Des. Ruan, 2016.

Figures

FIGURE 76. Chaetocnema angustifrons sp. nov. A Holotype, dorsal view. B Pronotum and peri-scutellar area. C Head, frontal view. D Aedeagus, ventral view. E Aedeagus, lateral view. F Apex of aedeagus, ventral view. G Vaginal palpi. H Spermatheca. I Pygidium (tergite 7) of female.