Atta cephalotes is the most widely distributed species of leaf cutting ant. It occurs from southernmost Mexico to Ecuador and Brazil, and from the Lesser Antilles as far north as Barbados (Hölldobler & Wilson, 1990). An apparently disjunct population occurs in the Atlantic Coastal Forests of Brazil (Solomon, 2007). The species is widely regarded as a significant pest on crops including citrus, coffee, cocoa and ornamentals (Cherrett, 1986; Cherrett & Peregrine, 1976). The ecological success and ubiquity of A. cephalotes is owed in large part to its broad niche tolerance with respect to both nesting habitats and diet breadth (Solomon, 2007). The species has evolved to specialize in forest gaps, and consequently thrives in disturbed habitats such as farms and plantations (Cherrett & Peregrine, 1976). Niche modeling suggests that the current range of A. cephalotes is limited by dispersal constraints rather than suitable habitat (Solomon, 2007), and could cause significant ecological and agricultural devastation should it become introduced elsewhere (Hölldobler & Wilson, 1990; Mikheyev, 2008). A pest risk assessment of unprocessed Eucalyptus concluded the introduction of South American Atta species into the United States was a low probability (Kliejunas et al., 2001).
The species is widely regarded as a significant pest on crops including citrus, coffee, cocoa and ornamentals.
Diagnosis of worker among Antkey species. Antenna 11-segmented. Antennal club indistinct. Antennal insertions at least partly covered by frontal lobes. Antennal scrobe lacking. Antennal scapes not conspicuously short; easily extended beyond eye level. Posterolateral corners of head spinose; lacking pair of small teeth anterior to posterolateral spines. Head smooth and shiny, not covered by hexagonal microsculpture. Head of soldier appearing wooly, covered in abundant long fine overlapping hairs. Mandibles triangular. Waist 2-segmented. Petiole with a distinct and upright node. Postpetiole attached to lower surface of gaster. Dorsum of promesonotum with 2 pairs of spines or teeth. Propodeum armed with spines. First gastral tergite lacking numerous tubercles. Yellow to reddish brown.
Atta cephalotes is highly variable, both among castes of the same colony and across populations. Workers vary enormously in shape, color, sculpture and pubescence (Borgmeier, 1959). The species is most readily confused with A. sexdens, but can be distinguished by the wooly hairs on the heads of major workers and the shinier integument caused by the lack of hexagonal microsculpture, and the lack of small teeth or dents on the head anterior to the posterolateral spines. The pronotal spines of A. cephalotes tend to be more curved than those of its congeners, but this is a highly variable character.
The majors of A. cephalotes are also distinguished from its two congeners native to the United States (A. mexicana and A. texana) by the presence of wooly hairs on the cephalic dorsum. The petiolar spiracles are visible from above in the two native species, but cannot be seen from above in A. cephalotes (Borgmeier, 1959). Atta cephalotes is distinguished from its close relatives in the genus Acromyrmex by the presence of only three long spines on the mesosomal dorsum, and the absence of tubercles on the mesosomal and gastric dorsum.
Atta sexdens, Acromyrmex octospinosus.
Native range. Southernmost Mexico to Ecuador and Brazil, and from the Lesser Antilles as far north as Barbados.
Introduced range. No records of introductions.