Aphaenogaster 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 : 12

Aphaenogaster Mayr , 1853

Taxonomy. The genus Aphaenogaster is assigned to the tribe Pheidolini (Bolton 2003). Workers of Vietnamese species have the following features.

Worker monomorphic; head in full-face view oval or elliptical, often with extremely elongate neck; frontal carina, if distinct, not extending beyond the level of eye in full-face view; antennal scrobe absent; parafrontal ridge or carina(e) often present; median portion of clypeus convex anteriad, sometimes with a shallow emargination at midpoint; posteromedian portion of clypeus moderately or relatively broadly inserted between frontal lobes; masticatory margin with apical and 2 distinct preapical teeth followed by several smaller teeth or denticles; palp formula 5,3 or 4,3; antenna 12-segmented, gradually incrassate toward apex or with an indistinct 4-segmented club; eye medium sized; mesosoma elongate; promesonotum forming a dome; promesonotal suture weakly present or absent dorsally; metanotal groove moderately or strongly impressed dorsally; propodeal spines varying in size and shape (rarely reduced to tiny denticles or rounded angles); propodeal lobe round or subtriangular with blunt angles; petiole consisting of an anterior peduncle and a node (separation between peduncle and node sometimes indistinct); gastral shoulder absent.

The worker of Aphaenogaster is similar to the minor worker of Pheidole (larger species) and the worker of Kartidris and Myrmica . In the minor worker of Pheidole the masticatory margin of the mandible bears 1 or 2 small teeth between the preapical tooth and the 3rd large tooth. In the worker of Kartidris the vertex has a broad depressed area between eyes, the masticatory margin of the mandible has 5 distinct teeth, the antennal club is distinctly 3-segmented, and the propodeum is unarmed. In the worker of Myrmica the promesonotum is only slightly raised and the propodeal lobe is well-developed as a triangular or sharp lamella. In addition, the palp formula is always 6,4 in Myrmica as opposed to 5,3 or 4,3 in Aphaenogaster .

Vietnamese species. Twelve species have been recognized by us from Vietnam: exasperata Wheeler [= sp. eg- 22] (Ba Be, Cuc Phuong, Pu Mat, Tay Yen Tu, Van Ban); sp. eg-1 (Sa Pa); sp. eg-2 (Sa Pa); sp. eg-3 (Sa Pa); sp. eg-4 (Sa Pa); sp. eg-6 [= sp. eg-15 in Eguchi et al. 2005] (Ba Vi, Sa Pa); sp. eg-10 (Phu Quoc); sp. eg-17 [= sp. 25 of SKY in Yamane et al. 2003] (Cuc Phuong, Ky Thuong, Pu Mat, Tay Yen Tu); sp. eg-18 [= sp. 22 of SKY in Yamane et al. 2003; = sp. eg-6 and sp. eg-15 in Eguchi et al. 2005] (Ba Vi, Cuc Phuong, Pu Mat, Tam Dao, Tay Yen Tu); sp. eg-21 (Tam Dao); sp. eg-25 (Nui Chua); sp. eg-26 (Van Ban).

Bionomics. The majority of species inhabit well-developed forests but some occur in sparse forests, dwarf forests and areas with low bushes. Nests are usually found in the soil, under stones and in rotting logs (Bui & Eguchi 2003, Eguchi et al. 2004).