These keys to genera of Pseudomyrmecinae have been modified from Ward, 1990.

The following measurements (all in mm) and indices are used in the keys.

HW - maximum width of head, including the eyes
EL - eye length: length of the compound eye, measured with the head in full-face (frontal) view
EW - eye width: maximum width of the compound eye, measured along the short axis in an oblique dorsolateral view of the head
MD5 - length of the basal margin of the mandible
MD9 - length of the masticatory margin of the mandible
OI - ocular index: EW/EL

Workers and Queens

1

Antennae 12-segmented; metabasitarsal sulcus variable, always absent in New World species => 2
Antennae 11-segmented; metabasitarsal sulcus present; Brazil, Guyana => Myrcidris

Metabasitarsal sulcus of Myrcidris worker.

Mandible nearly always with proximal tooth on basal margin (pbt in figure); eyes elongate, width two-thirds or less than length (OI 0.50-0.66); metabasitarsal sulcus lacking; southern Nearctic, Neotropical (one species introduced to Hawaii) => Pseudomyrmex

Mandible with proximal tooth.

Mandible lacking proximal tooth on basal margin; eyes less elongate, width two-thirds or more than length (OI 0.67-0.95); metabasitarsal sulcus usually present; Paleotropical => Tetraponera

Mandible lacking proximal tooth.

Antennae 12-segmented; posterior margin of sternum VIII emarginate; external face of aedeagus lacking cornuti => 2
Antennae 13-segmented; posterior margin of sternum VIII broadly convex; external face of aedeagus with cornuti; Brazil, Guyana => Myrcidris

Masticatory margin of mandible with 6-18 teeth or denticles (or very rarely edentate), those preceding the apical tooth often quite small and abraded; if only 6 teeth present, then species small in size (HW < 0.98); basal margin of mandible one half or less the length of the masticatory margin (MD5/MD9 < 0.56), the two converging angularly at the apicobasal tooth or corner; New World => Pseudomyrmex
Masticatory margin of mandible usually with 2-5 teeth, typically subequal in size; rarely with 6 teeth, in which case HW > .99; basal margin of mandible two-thirds or more the length of the masticatory margin (MD5/MD9 < 0.64), the juncture between the two angular or rounded; Old World => Tetraponera

Ward, P. S. 1990. The ant subfamily Pseudomyrmecinae (Hymenoptera: Formicidae): generic revision and relationship to other formicids. Syst. Entomol. 15: 449-489.