Aenictus

Aenictus occurs throughout Africa and in tropical and subtropical areas from India east through southern China to Taiwan and south to Australia with outlier, temperate-climate species or populations in Japan, Afghanistan, Armenia and south-central Australia (Bolton et al., 2006; Gotwald, 1995; Shattuck, 1999, 2008). While widespread, nowhere are they common. All known species are "army ants" and conduct raids using large numbers of workers, primarily attacking other ants, social wasps and termites. While there are reports of these ants preying on other insects and even collecting honeydew from homopterans (Santschi, 1933; Gotwald, 1995), these habits appear to be uncommon.

Foraging raids undertaken by these ants occur both day and night, usually across the ground surface but occasionally also arboreally. During raids, numerous workers attack a single nest or small area, with several workers coordinating their efforts to carry large prey items back to the nest or bivouac. They also have a nomadic life style, alternating between a migratory phase in which nests are temporary bivouacs in sheltered places above the ground and a stationary phase where semi-permanent underground nests are formed. During the nomadic phase bivouacs move regularly, sometimes more than once a day when larvae require large amounts of food. Individual nests usually contain up to several thousand workers, although nest fragments containing only a few hundred workers are often encountered. Queens are highly specialised and look less like workers than in most ant species. They have greatly enlarged gasters and are termed dichthadiform. New colonies are formed by the division of existing colonies rather than by individual queens as in most ant species.

Aenictus is the only extant genus in the subfamily Aenictinae. It contains just over 150 valid species and subspecies (Bolton et al., 2006). The phylogenetic relationship of Aenictus to other ants has been investigated by Bolton (1990), Baroni Urbani et al. (1992), Brady (2003), Brady and Ward (2005), Brady et al. (2006), and Moreau et al. (2006).

Identification
Workers of Aenictus may be separated from other ants by their moderately small size (less than about 4 mm), lack of eyes, long slender bodies and long legs. They are superficially similar to some myrmicines but differ in lacking the frontal lobes and in having the antennal sockets completely visible when viewed from the front (myrmicines have frontal lobes that are expanded towards the sides of the head and partly cover the antennal sockets). Some of the smaller, paler species are also similar to Leptanilla workers, but differ in being larger and only ten segments in the antennae rather than 12, and lacking a flexible promesonotal suture.

Males of Aenictus can be separated from those of other ants by the exposed antennal sockets and lack of a postpetiole (the gaster is smooth and lacks a constriction between the first and second segments).

Identification Keys
Australia

Key to Aenictus species groups