Chaetocnema (Chaetocnema) sumatrana Jacoby, 1896

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 : 105-107

40. Chaetocnema (Chaetocnema) sumatrana Jacoby, 1896

( Fig. 61 )

Chaetocnema sumatrana Jacoby, 1896: 440 . TL: Sumatra. TD: BMNH. Lectotype designated here.

Distribution: China, Singapore, Philippines, Indonesia (Sumatra).

Host plants: Unknown.

Description: Body length: 2.90–3.20 mm. Body width: 1.70–1.75 mm. Ratio of elytron length (along suture) to width (maximum): 2.55–2.60. Ratio of pronotum width (at base) to length: 1.70–1.75. Ratio of length of elytron to length of pronotum (along middle): 2.80–2.90. Ratio of width of elytra at base (in middle of humeral calli) to width of pronotum at base: 1.09–1.11.

Elytra red brown, pronotum and head deep red brown. Pronotum and head finely reticulated. Antennae completely yellow brown, with distal ones slightly darker. Color of all legs red brown, except tarsi yellow.

Head hypognathous. Frontal ridge moderately wide, slightly convex. Frontolateral sulcus present. Suprafrontal sulcus moderately developed. Shallow mid-cranial suture evident in some specimens. Supraantennal, orbital sulci not very deep. Ratio of width of frontal ridge (excluding margin) to width of antennal socket (excluding margin): 1.70–1.80. Three to five weak punctures present on vertex on each side near eye. Orbit narrow, glabrous, occasionally with a few small rugged punctures. Number of setae on clypeus: 15-20. Number of setae on labrum: 6. Anterior margin of labrum slightly convex.

Pronotum with two extremely obscure, barely visible longitudinal impressions near basal margin. Deep row of large punctures at base of pronotum absent. Pronotal base convex, slightly expanded at middle. Lateral margins of pronotum straight, converging forward. Anterolateral prothoracic callosity truncate and oblique, moderately developed. Posterolateral prothoracic callosity poorly developed. Diameter of pronotal punctures 2 to 3.5 times smaller than distance between them.

Elytra generally convex at lateral sides. Elytral punctures larger than those on pronotum, arranged in single rows, including peri-scutellar row. Interspaces between striae of punctures strongly costate. Number of rows of minute punctures on each interspace: 2–3. Humeral callus well developed.

Excavation on tibia very deep, tooth before excavation long and acute.

Apex of aedeagus in ventral view narrowing gradually. Ventral longitudinal groove absent. In ventral view, apex of aedeagus streaked with oblique wrinkles and grooves, which is unique amongst Oriental Chaetocnema species. Apical denticle in ventral view moderately developed. Minute transverse wrinkles on ventral side absent. Aedeagus in lateral view unevenly curved, more or less straight near apex, maximum curvature in lateral view situated at base.

Types: Lectotype: 1 ( BMNH), 1) Type H. T.; 2) Sumatra, PANGHERANG—PISANG, X.90 – III.91, E. MODI- GLIANI; 3) Jacoby Coll., 1909–28 a; 4) Chaetocnema sumatrana Jacoby ; 5 ) Lectotype Chaetocnema sumatrana Jacoby, 1896 Des. Ruan et al., 2016 .

Paralectotype: 2♂ ( BMNH), 1) Sumatra, PANGHERANG–PISANG, X.90 – III.91 , E. MODIGLIANI; 2) Ja- coby Coll. , 1909–28 a.; 3) Paralectotype Chaetocnema sumatrana Jacoby, 1896 Des. Ruan et al., 2016 .

Material: 1♂ 3♀, China, Xishuanbanna, Yunnan, VII–IX.1958, Chaetocnema sumatrana Jacoby, 1896 det. Ruan, 2016 ( IZCAS) .

Remarks: Chaetocnema wallacei , C. sumatrana and C. montivaga are very close to each other. Chaetocnema wallacei differs from C. sumatrana and C. montivaga by its larger body size. Body length of C. wallacei is about 4.0 mm, while C. sumatrana and C. montivaga are much smaller, usually about 3.2 mm. Chaetocnema wallacei could also be differentiated from the latter two species by the following characters: body obviously narrower; elytra extremely narrow and long; base of elytra hardly wider than that of pronotum; pronotum with fairly dense and minute punctures.

In C. sumatrana and C. montivaga , there are two oblique ridges on the ventro-lateral side of aedeagus. However, the oblique ridges in C. montivaga are much weaker than in C. sumatrana .

Figures

FIGURE 61. Chaetocnema sumatrana. A Lectotype, habitus. B Head of Lectotype, frontal view. C Pronotum and peri-scutellar area of Lectotype. D Aedeagus, ventral view (Paralectotype). E Aedeagus, lateral view (Paralectotype). F Apex of aedeagus, ventral view (Paralectotype). G Middle part of aedeagus, ventral view (Paralectotype). H Hand drawing of middle part of aedeagus, red arrow indicates wing like ridges. I Middle part of aedeagus, lateral view, red arrow indicatswing like ridges (Paralectotype).