Acanthomyrmex

Eguchi, Bui and Yamane (2011) -Acanthomyrmex species nest in dead twigs and wood fragments, and under or between stones. Colonies of Acanthomyrmex glabfemoralis contain a single dealate normal queen, or instead contain single or multiple dwarf queens, while colonies of A. humilis contain ergatoid queens only (Eguchi et al. 2008). Acanthomyrmex glabfemoralis and Acanthomyrmex humilis gather seeds (Eguchi et al. 2004, Eguchi pers. observ.).

Identification
Eguchi, Bui and Yamane (2011) -Workers of Vietnamese species have the following features (see also Moffett 1986; Eguchi et al 2008): Worker dimorphic; frontal lobe reduced, in full-face view only partially concealing the torulus; frontal carina present, usually conspicuous; antennal scrobe present, usually conspicuous; anteromedian margin of clypeus weakly convex with a shallow median emargination in major; anteromedian margin of clypeus always armed with 2 to several processes in minor; median clypeal seta reduced or absent in major, but always present in minor; lateral portions of clypeus not forming a conspicuous ridge in front of torulus in major, but raised into a ridge in front of torulus in minor; mandible in major massive, edentate or armed with a few indistinct teeth on masticatory margin; mandible in minor broadly triangular, and armed with 5–10 small to tiny teeth in addition to relatively conspicuous apical and preapical teeth; antenna 12-segmented, with 3-segmented club; eye moderately developed; mesosoma short and robust especially in major; promesonotal suture absent dorsally; metanotal groove obsolete or shallow dorsally; propodeum armed with a pair of long spines; propodeal lobe well developed, angulately produced poster¬odorsad; petiole pedunculate anteriorly and with distinct node; postpetiole much shorter than petiole; suture between first gastral tergite and sternite basally in the form of a rounded M-shape; postpetiole articulated at base of the M.

The minor worker of Acanthomyrmex is similar to the worker of Pristomyrmex, but in the latter the antenna is 11-segmented, the masticatory margin of the mandible is almost vertical to the basal margin and 3-, 4- or 5-toothed, and the suture between first gastral tergite and sternite is not in the form of a rounded M-shape.

Biology
Acanthomyrmex species nest in cavities in dead twigs and wood fragments, under or between stones and in litter on the forest floor, and their colony size is usually small (Moffett 1985, Terayama et al. 1998, Eguchi et al. 2004). We often encounter patches in which colonies are aggregated. Because reproduction by ergatoids is dominant in some species of Acanthomyrmex (Terayama et al. 1998), such aggregation of colonies may be caused by the low dispersal ability of the ergatoid founder. The species in this genus are worker-dimorphic: the major worker is a seed-miller (Moffett 1985).

Nomenclature

 *  ACANTHOMYRMEX [Myrmicinae: Myrmecinini]
 * Acanthomyrmex Emery, 1893a: cclxxvi. Type-species: Acanthomyrmex luciolae, by subsequent designation of Bingham, 1903: 191.
 * [Acanthomyrmex also described as new by Emery, 1893f: 244].