Diagnostic Features - Dimorphic, intermediates rare. Major worker, often called a soldier, with a massive head and the occipital margin deeply impressed centrally. Eyes forward of the mid-length of the head. Promesonotal suture rarely present. Metanotal groove deeply impressed.
Petiole usually emarginate dorsally.
Minor worker with the occipital margin shallowly emarginate or more usually with the sides of the head converging behind the eyes, to give a very short occipital margin. Mandibles usually with two or three large apical teeth subtended by a row of denticulae. Remainder as in the soldier, but the eyes are usually at about or just forward of the midlength of the head. A very large and taxonomically confused genus, with a multiplicity of nesting sites and foraging habits. Because of the relative similarity of males, queens and workers, he found the soldiers with distinct variations to be the only useful form for distinguishing species.