Key to US Atta species

Key to Atta species of the United States based on workers.


 * Posterior cephalic lobes and first gastral tergite lacking erect hairs, the surface shiny; concavity between cephalic lobes relatively shallow, the angle between its sides more than 90 degrees; pronotal spines relatively short => Atta mexicana


 * Posterior cephalic lobes and first gastral tergite with hairs, the surface matte; concavity between cephalic lobes relatively deep, the angle between its sides less than 90 degrees; pronotal spines relatively long => Atta texana