Chaetocnema (Chaetocnema) excavata Medvedev, 1997

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 : 47-48

10. Chaetocnema (Chaetocnema) excavata Medvedev, 1997

( Fig. 29 )

Chaetocnema excavata Medvedev, 1997: 21 . TL: Nepal (Lamobagar Gola, Arun Valley). TD: NHMB.

Distribution: Nepal (Lamobagar Gola, Arun Valley), India.

Host plants: Unknown.

Description: Body length: 2.50–3.30 mm. Body width: 1.30–1.70 mm. Antennae elongate, stretching to the middle of elytra, ratio of length of antenna to length of body: 0.75–0.80. Ratio of elytron length (along suture) to width (maximum): 2.40–2.50. Ratio of pronotum width (at base) to length: 1.45–1.50. Ratio of length of elytron to length of pronotum (along middle): 2.40–2.50. Ratio of width of elytra at base (in middle of humeral calli) to width of pronotum at base: 1.10–1.15.

Body elongate, different from most Chaetocnema species. Color of dorsal surface bronzy. Antennomeres 1–4 completely yellow brown, the remaining ones brown black. Femur brown, tibiae and tarsi yellow brown.

Head hypognathous. Frontal ridge moderately wide, convex. Frontolateral sulcus present, but short. Suprafrontal sulcus poorly developed. Orbital sulcus deep. Ratio of width of frontal ridge (excluding margin) to width of antennal socket (excluding margin): 1.40–1.45. One large puncture bearing setae on each side near eye, a few minute punctures scattered on vertex. Number of punctures on orbit: 1–2 on each side. Number of punctures on frons (triangular area surrounded by frontolateral sulcus and clypeus): 0. Number of setae on clypeus: approximately 10. Number of setae on labrum: 6. Anterior margin of labrum slightly convex at middle.

Pronotum without longitudinal impressions near basal margin. Deep row of large punctures at base of pronotum absent. Pronotum more or less quadrate. Pronotal base almost straight or slightly sinuated. Lateral margins of pronotum slightly convex, not converging forward. Anterolateral prothoracic callosity more or less truncate. Posterolateral prothoracic callosity poorly developed. Diameter of pronotal punctures 2 to 4 times smaller than distance between them. Pronotal punctures scattered, rugged.

Elytra with sides more or less parallel. Elytral punctures slightly larger than those on pronotum. Punctures on elytra arranged in single regular rows, including peri-scutellar row. Interspaces between rows of punctures smooth, glabrous. Humeral callus well developed.

First male protarsomere larger than that of female, slightly larger than second. Excavation on metatibia extremely deep. Large lateral denticle on metatibia elongate, forming a process. Metatibial serration proximal to large lateral denticle absent or poorly developed.

Apex of aedeagus in ventral view narrowing abruptly. Ventral longitudinal groove poorly developed. Apical denticle in ventral view sharp and narrow. Minute transverse wrinkles on ventral side absent. Aedeagus in lateral view slightly curved. Maximum curvature in lateral view situated at apex and base.

Spermathecal receptacle oblong. Spermathecal duct coiled. Spermathecal pump shorter than receptacle, with apex pointed. Vaginal palpus (before apex) slightly narrowing from base till middle, thence approximately parallel-sided. Anterior sclerotization of vaginal palpus slightly narrowing anteriorly. Posterior sclerotization longer than wide. Posterior sclerotization wider than anterior.

Type: 1♀ (Holotype) ( NHMB), 1) Lamobagar Gola, 1400m, 28–31.V; 2) O–Nepal, Arun V.1980, C. Hol- zschuh; 3) Chaetocnema det. L. Medvedev ; 3) Holotypus Chaetocnema excavata m. L. Medvedev det. 1996.

Material: 3♂ 3♀ ( USNM), Nepal, Pokhara–Kathmandu road, env. Damauli , Seti river 24.IV.2000, Konstantinov, Lingafelter, Volkovitsh ; 1♂ ( BMNH), India, Namsoo, Darjeeling , 2100 ft., 18.VI.1918, H. Stevens, Stevens Coll., B. M. 1916–218 .

Remarks: Chaetocnema excavata may be differentiated from its congeners by the cylindrical body shape, comparatively longer antennae and deep hind tibial excavation.

Figures

FIGURE 29. Chaetocnema excavata. A Male habitus. 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.