Opamyrma hungvuong

This is the only species in the genus Opamyrma.

Identification
Yamane et al. (2008) - Opamyrma is similar to Apomyrma with several shared characteristics: the outer face of the labrum bears peglike teeth; the frontal lobe is absent; the antennal socket is directed almost dorsad; the sternite of the petiole is reduced to a small posteroventral sclerite, bounded by the conspicuous tergo-sternal sutures; and the third abdominal segment above the helcium has a free anterior face.

The features which separate Opamyrma from Apomyrma (see Brown et al 1971; Bolton 1990, 2003 for characterization of Apomyrma) are: preoccipital carina complete, almost encircling the head slightly before its posterior margin; clypeus posteriorly margined with a distinct continuous carina; petiole without a distinct anterior peduncle; abdominal segment III longer than IV, V and VI; segment VII longest among the segments III–VII; anteriormost part of abdominal sternite III produced anteriad to the same level as the anteriormost part of tergite III; segment IV with differentiated presternite.

Distribution
Central Vietnam.

Distribution based on Regional Taxon Lists
Oriental Region: Vietnam.

Nomenclature

 *  hungvuong. Opamyrma hungvuong Yamane, Bui & Eguchi, 2008: 57, figs. 1-12 (w.) VIETNAM.

Worker
Measurements and indices (holotype and paratype; those for paratype shown in parentheses). Head length (as measured from the anterior margin of clypeus to the posterior margin of head in full-face view) 0.73 mm (0.71); head width (maximum width of head in full-face view) 0.55 mm (0.55); cephalic index (head width/head length x 100) 75 (77); scape length (length of antennal scape excluding the basal condylar bulb) 0.38 mm (0.38); scape index (scape length/head width x 100) 69 (69); mesosomal length (as measured from the anterior margin of pronotum to the posterior margin of propodeum in profile) 1.12 mm (1.12); hind femur length (maximum length of hind femur) 0.50 mm (0.49); hind femur index (hind femur length/head width) 91 (89).

Head long, almost rectangular, with slightly convex lateral margins and almost straight posterior margin in full-face view; in profile flattened dorsoventrally. Median part of clypeus with anterior margin weakly and broadly concave. Mandible slender, strongly curved at the apical end of trulleum (this can be clearly observed when the mandibles are opened); basal two-thirds almost parallel-sided in outer view (Fig. 5), with long but bluntly tapered apical tooth followed by a trapezoidal lobe (probably fusion of two preapical teeth: “mtl” in Fig. 3) and three inconspicuous teeth. Antennal scape (segment I) flattened dorsoventrally, narrowed toward base; segment II bead-like, in frontal view strongly narrowed at base (“as-II” in Fig. 2); segment III slightly longer than broad and narrowed basally; segments IV and V almost as long as broad; segments VI–XI broader than long; apical segment longer than broad and bluntly pointed at apex.

Pronotum longer than broad in dorsal view, with slightly convex dorsal face that merges into lateral face roundly; anterior slope short and steep. Remaining portion of mesosoma slightly narrower than pronotum and almost parallel-sided in dorsal view; nota and pleura roundly continuous; mesopleuron separated from metapleuron by a sulcus; lower portion of metapleuron defined posteriorly by a narrow furrow; propodeum with rather flat dorsum and steep posterior face.

Femur and tibia of fore leg broader than those of mid- and hind legs; relatively broad gap present between mid- and hind coxae.

Petiole seen from above much longer than broad, slightly narrowed posteriad, and laterally weakly convex, in profile much longer than high, weakly converging posteriad.

Gaster with a long and up-curved sting.

Whole body only weakly sculptured and moderately shining; mandible with sparse large punctures which generally bear setae; dorsum of head superficially punctate; clypeus with posterior portion almost unsculptured and shining; mesosoma more weakly sculptured than dorsum of head, with posteroventral portion of its side irregularly sculptured; petiole and gaster almost smooth and shining.

Head with dense short hairs that are erect or suberect; mandible when closed with lower margin bearing relatively long and sparse standing hairs; antennal scape with sparse erect hairs in addition to denser short pubescence; hairs on funiculus generally short, especially on apical segments; mesosoma and petiole dorsally with sparser standing hairs; erect hairs on tibiae and tarsi shorter than those on femora; gastral terga dorsally with standing hairs that are denser than those on mesosoma; gastral sterna each with isolated erect hairs.

Whole body light brown, with antennae and legs slightly yellowish.

Type Material
Holotype (worker): 21 Feb. 2000, Rao An, Son Kim II Commune (18°31'N; 105°27'E), Huong Son District, Ha Tinh Province, northern part of Central Vietnam, leg. T.V. Bui. Paratype: 1 worker, same data as in the holotype (KMNH).

Etymology
The specific name hungvuong derives from the legendary king Hung Vuong who founded the first Vietnamese state Van Lang.