Labomimus cavicornis sp. nov.

(Figs 1A, 2)

Type material (6 specimens). HOLOTYPE: VIETNAM: ĐỒNG NAI: ♂, ‘S-VIETNAM, Nam Cat Tien Nat. Park, 1.- 15.5.1994, Pacholatko & Dembicky’ (MHNG) . PARATYPES: VIETNAM: ĐỒNG NAI: 5 ♂♂, same label data as for holotype (MHNG, SNUC) .

Diagnosis. Male body length 3.09–3.23 mm. Antennomere 9 with broad depression in apical half, with disc-like impression inside depression; antennomeres 10 broadly depressed and antennomere 11 deeply concave on ventral side. Horn-like metaventral processes in lateral view elongate and bifurcate at apices. Protibia with short, blunt preapical projection; mesotrochanter with acute ventral spine. Median lobe of aedeagus asymmetric, narrowing apically; parameres broad at bases and narrowed in apical halves; endophallus with spine-like structures and one elongate sclerite. Female unknown.

Description. Male (Fig. 1A). Body length 3.09–3.23 mm. Head slightly broader than long, HL 0.56–0.61 mm, HW 0.59–0.63 mm; eyes prominent, each composed of about 41 facets. Antennomeres 2–8 of similar shape, each moniliform; antennomeres 9–11 (Fig. 2A) forming distinct club; antennomere 9 with large depression in apical half, and one disc-like impression inside depression; antennomeres 10 broadly depressed and antennomeres 11 with broad and deep concavity on ventral side. Pronotum (Fig. 2B) approximately as long as wide, PL 0.56 mm, PW 0.56–0.59 mm, narrowed anteriorly at apical 2/5. Elytra broader than long, EL 0.87–0.94 mm, EW 1.11–1.15 mm. Horn-like metaventral processes (Fig. 2C) in lateral view elongate and curved upward, bifurcate at apices. Protrochanter (Fig. 2D) with tiny ventral tooth; profemur angularly expanded at middle; protibia (Fig. 2E) with blunt process before apex; mesotrochanter (Fig. 2F) with acute ventral spine; mesofemur (Fig. 2F), metatrochanter and metafemur (Fig. 2G) simple.Abdomen broad at base and narrowed apically, AL 1.00– 1.02 mm, AW 1.11–1.20 mm. Sternite 7 (IX) (Fig. 2H) hemi-membranous, elongately oval. Aedeagus (Figs 2I –E) 0.55 mm long; median lobe asymmetric dorso-ventrally, narrowing apically; parameres short, curved ventrally, broad at bases and abruptly narrowed for apical halves; endophallus comprising one large, elongate and curved sclerite, and numerous hemi-membranous spinelike structures at apical part.

Female. Unknown.

Comparative notes. This is a very distinctive species which can be easily separated from all congeners by unique modification of the male antennal club.

Etymology. The new species is a Latin adjective composed of cavus (- a, - um; meaning hollow, concave, excavated) and cornis (- is, - e; meaning horned), referring to the strongly depressed and concave antennal clubs of the male.

Distribution. Vietnam: Đồng Nai.