Opamyrma, Yamane, Seiki, Bui, Tuan Viet & Eguchi, Katsuyuki, 2008

Yamane, Seiki, Bui, Tuan Viet & Eguchi, Katsuyuki, 2008, Opamyrma hungvuong, a new genus and species of ant related to Apomyrma (Hymenoptera: Formicidae: Amblyoponinae), Zootaxa 1767, pp. 55-63 : 56

Opamyrma gen. n.

( Figs. 1–12 )

Type species. Opamyrma hungvuong sp. n.

Worker description. Preoccipital carina complete, almost encircling the head slightly before its posterior margin (“poc” in Fig. 4 ). Venter of head with a distinct and complete median furrow, with each anterolateral corner forming a process (“alc” in Fig. 3 ). Clypeus posteriorly margined with a distinct continuous carina (“pcc” in Fig. 3 ); median part of clypeus rather clearly divided into posterior horizontal portion and anterior steep slope; the posterior portion broadly inserted between antennal sockets, extending anteriorly to the level of posterior margin of the sockets; lateral part of clypeus narrow from front to back. Mandibular base with closed trulleum (“trl” in Fig. 3 ). Labrum on its outer face with at least two rows of peg-like denticles, each with more than 10 denticles (“lpd” in Fig. 3 ). Eye absent. Frontal lobe absent. Antennal sockets completely exposed in full-face view, directing almost dorsad, located in a large, roundly excavated area whose anterior wall is steep just behind the posterior margin of clypeus; the area not clearly defined posteriorly. Antenna 12- segmented, gradually incrassate from segment II to XII.

Mesosoma elongate, with a single furrow (“msf” in Figs. 6 & 7 ) which is deep and flexible and separates pronotum from the remaining part of mesosoma. Metapleural gland bulla round, occupying posterior twofifths of ventrolateral part of the pleuron; metapleural trench running below the bulla. Junction of dorsal and posterior faces of propodeum round without any transverse carina; posterior face of propodeum laterally without spines/carinae. Propodeal spiracle situated relatively low on the side of propodeum, near the weak furrow separating metapleuron from lateral side of propodeum. Propodeal lobe present, low and round.

Mid- and hind tibiae each with a reduced barbulate anterior spur (“ats” in Fig. 8 ) and a well-developed pectinate posterior spur (“pts” in Fig. 8 ). Pretarsal claws simple, without teeth.

Waist consisting of a single segment (petiole); petiole elongate, narrowly attached to abdominal segment III (gastral segment I), virtually without anterior peduncle; tergo-sternal sutures of petiole present as longitudinal furrows on ventrolateral edges that meet medially at 1/3 length of petiole from the base (“tss” in Fig. 10 ); the sternite of petiole reduced to a small posteroventral sclerite, bounded by the conspicuous tergo-sternal sutures; petiolar spiracle located anteriorly on the lateral face of petiole at its mid-height.

Gaster very long, laterally compressed, especially in posterior portion, in profile highest at the posterior end of abdominal segment VI (“absg-VI” in Fig. 11 ). Segment III (“absg-III” in Fig. 11 ) seen from above longer than broad, narrowed basally, longer than segments IV, V and VI, having a free anterior face above the helcium; anteriormost part of abdominal sternite III (“abs-III” in Fig.11 ) produced anteriad to the same level as the anteriormost part of tergite III (“abt-III” in Fig. 11 ). Segment IV with differentiated presternite (“ps-IV” in Fig. 11 ). Spiracles on segments V–VII concealed by the preceding segments. Segment VII (“absg-VII” in Fig. 11 ) longest among the segments III–VII. Pygidium (“abt-VII” in Fig. 11 ) and hypopygium (“abs-VII” in Fig. 11 ) unarmed.

Figures

FIGURES 1 – 3. Opamyrma hungvuong gen. & sp. n., holotype (worker) — 1, body in profile; 2, head in full-face view (as-II: antennal segment 2); 3, anterior part of head in anterodorsal view (alc: anterolateral corner, lpd: peg-like denticles on labrum, mtl: mandibular tooth 1, pcc: posterior carina of clypeus, trl: trulleum).

FIGURES 4 – 6. Opamyrma hungvuong gen. & sp. n., holotype (worker) — 4, head in profile (poc: preoccipital carina); 5, left antenna and left mandible in outer view; 6, mesosoma in profile (msf: mesosomal furrow).

FIGURES 7 – 9. Opamyrma hungvuong gen. & sp. n., holotype (worker) — 7, mesosoma and petiole in dorsal view; 8, tibial spurs of left hind leg in anterior view (ats: anterior spur, pts: posterior spur); 9, pretarsal claws of left hind leg.

FIGURES 10 – 12. Opamyrma hungvuong gen. & sp. n., holotype (worker) — 10, petiole in profile (tss: tergo-sternal suture); 11, gaster in profile (abs: abdominal sternite, absg: abdominal segment, abt: abdominal tergite, ps: presternite); 12, gaster in dorsal view.