Atopomyrmex Ern. André Worker variable in size, but only feebly polymorphic, with 12-jointed antennae and 3-jointed antennal club. Clypeus subtriangular; moderately and evenly convex, its anterior border feebly notched in the middle and on the sides. Frontal area and groove distinct. Frontal carinae far apart, in the large workers continued back some distance as diverging ridges bordering scrobe-like impressions for the antennal scapes. Mandibles triangular, convex, with toothed apical margins. Eyes small, flat, nearly circular, placed near the middle of the sides of the head. Ocelli absent. Pronotum flattened above with rectangular humeri. Promesonotal suture indistinct. Mesonotum bituberculate; separated from the epinotum by a wide and deep constriction. Epinotum armed with two long diverging spines; its base bituberculate anteriorly. Petiole and postpetiole very small, the node of the former bispinose above; postpetiole transverse with distinct anterior angles. Legs long and stout, femora incrassated in the middle; middle and hind tibiae without spurs. Gaster broadly elliptical, somewhat compressed dorsoventrally. Body without erect hairs; pubescence extremely short and sparse, appressed. Female considerably larger than the worker. Scrobe-like impressions of the head more distinct. Antennae 12-jointed. Eyes small, but larger than in the worker; ocelli very small, close together. Thorax short, through the wing insertions slightly narrower than the head. Pronotum visible from above as the mesonotum is rather small and flat. Epinotum abrupt, without distinct base and without spines. Petiolar spines reduced to two blunt tubercles. Gaster large, elongate, convex above and below, nearly as long as the remainder of the body. Anterior wings with a discoidal, a single cubital and a closed radial cell, with a distinct intercubitus (Solenopsis-type). Male with short, stout, denticulate mandibles. Head broad and long, much broader than the thorax and with marginate occipital border. Clypeus carinate. Frontal carinae strongly diverging. Eyes rather small, occupying only about one-fifth of the sides of the head. Antennae 13-jointed; scapes very short, scarcely two and onehalf times as long as broad; first funicular joint as broad as long, not swollen; remaining joints cylindrical. Epinotum and petiole unarmed. External genital valves long, triangular, pointed at the tip. Wings as in the female. This remarkable genus contains only a single species, which is widely distributed over the Ethiopian Region though not occurring elsewhere (Map 25).

Published as part of Wheeler, W. M., 1922, The ants collected by the American Museum Congo Expedition., pp. 39-269 in Bulletin of the American Museum of Natural History 45 on pages 180-181