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. It contains valid species and subspecies. 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), Moreau et al. (2006) and Brady et al. (2014).

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, i.e., the gaster is smooth and lacks a constriction between the first and second segments. There are dozens of Aenictus species that have been described from males only. It is at difficult to match such forms to their workers without collecting from a live colony that contains males. Such collections are atypical for many Aenictus ants hence recent taxonomic practice has been to place unassociated males, and these male-only based names, beyond the scope of revisionary work being completed.

Identification Keys

 * Australian Aenictus worker key
 * Key to Aenictus of Laos

Jaitrong and Hashimoto (2011, 2012) reformulated the species groups in the genus, based on worker morphology, and this is a great help when working through species determinations.


 * Key to Aenictus species groups
 * Aenictus species groups (diagnoses)

Species richness
Species richness by country based on regional taxon lists (countries with darker colours are more species-rich). View Data



Biology
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.

Castes
The majority of Aenictus  species are monomorphic, with a few exhibiting some weak polymorphism. Aenictus inflatus is unusual within the genus as it has a distinctly polymorphic worker caste. There are a large number of species that are only known from males and most of the species described from workers have yet to be associated with any known male specimens.

Nomenclature

 *  AENICTUS [Aenictinae]
 * Aenictus Shuckard, 1840b: 266. Type-species: Aenictus ambiguus, by original designation.
 * Aenictus senior synonym of Typhlatta: Forel, 1890b: ciii.
 * Aenictus senior synonym of Paraenictus: Wilson, 1964: 444.
 *  ENICTUS [unavailable name]
 * Enictus Walker, 1860: 306; Smith, F. 1865: 79; incorrect subsequent spellings of Aenictus: Bolton, 1995b: 19.
 * PARAENICTUS [junior synonym of Aenictus]
 * Paraenictus Wheeler, W.M. 1929g: 27 [as subgenus of Aenictus]. Type-species: Aenictus (Paraenictus) silvestrii, by monotypy.
 * Paraenictus junior synonym of Aenictus: Wilson, 1964: 444.
 * TYPHLATTA [junior synonym of Aenictus]
 * Typhlatta Smith, F. 1857a: 79. Type-species: Typhlatta laeviceps, by monotypy.
 * Typhlatta junior synonym of Aenictus: Forel, 1890b: ciii.
 * Typhlatta revived from synonymy as subgenus of Aenictus: Wheeler, W.M. 1930g: 198.
 * Typhlatta junior synonym of Aenictus: Wilson, 1964: 444.