Acanthomyrmex Emery

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 : 11

Acanthomyrmex Emery , 1893

Taxonomy. The genus Acanthomyrmex is assigned to the tribe Myrmecinini together with Myrmecina, Perissomyrmex and Pristomyrmex (Bolton 2003). 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 posterodorsad; 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.

Vietnamese species. One species described from Vietnam: humilis Eguchi, Bui & Yamane (type locality: Nam Cat Tien) and a second species recognized by us from Vietnam: glabfemoralis Zhou & Zheng (Chua Yen Tu, Cuc Phuong, Ky Thuong, Pu Mat, Tay Yen Tu, Van Ban).

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