Rhoptromyrmex Mayr

Eguchi, K., Viet, B. T. & Yamane, S., 2011, Generic synopsis of the Formicidae of Vietnam (Insecta: Hymenoptera), Part I - Myrmicinae and Pseudomyrmicinae., Zootaxa 2878, pp. 1-61 : 28

Rhoptromyrmex Mayr , 1901

Taxonomy. The genus Rhoptromyrmex is assigned to the tribe Tetramoriini (Bolton 2003). The genus was revised by Bolton (1986). Workers of Vietnamese species have the following features.

Worker monomorphic; head in full-face view cordate; frontal carina and antennal scrobe absent; anteromedian margin of clypeus broadly convex without any emargination at its midpoint, overhanging basal border of mandibular blade when mandibles closed, lacking an isolated median seta; posteromedian portion of clypeus very broadly inserted between frontal lobes; lateral portion of clypeus modified into a narrow and low ridge or wall in front of antennal insertion; mandible triangular; masticatory margin with apical and 1 or 2 larger preapical teeth followed by some smaller teeth or minute denticles; palp formula 3,2; antennae 12-segmented, with distinct 3-segmented club; eye relatively large; mesosoma relatively short and high; promesonotum in lateral view not or hardly raised; promesonotal suture absent dorsally; metanotal groove weakly impressed dorsally; mesopleuron marginate anteriorly with a carina that never develops into distinct flange projecting over basal part of forecoxa; propodeal spine long and spinose; propodeal lobe reduced to a low carina; petiole consisting of short and stout peduncle and relatively high node; gastral shoulder indistinct or absent; apex of sting with a small lamellate appendage; body bearing a few standing hairs which are short and blunt apically; head and mesosoma only weakly and finely rugose.

The worker of Rhoptromyrmex is similar to that of Tetramorium , but in the latter the head in full-face view is roughly oval or subrectangular, with posterolateral corners which are not or weakly produced and the propodeal lobe is well developed. In Vietnamese species of Tetramorium the palp formula is 4,3.

Vietnamese species. Three species have been found from Vietnam: wroughtonii Forel [= sp. eg-2; = sp. 1 of SKY: Eguchi et al. 2005] (Ba Vi, Cuc Phuong, Sa Pa, My Yen, Tam Dao, Tay Yen Tu, Van Ban); sp. eg-1 [= sp. 2 of SKY: Eguchi et al. 2005](Cuc Phuong, Sa Pa, Tam Dao, Tay Yen Tu); sp. eg-3 [= sp. 3 of SKY: Eguchi et al., 2005] (Tam Dao).

Bionomics. Vietnamese Rhoptromyrmex species inhabit forest edges and woody habitats, but sometimes open habitats. They nest in soil and build a large caldera-shaped entance mound with soil particles.