Mexico to Panama.
In Costa Rica this species prefers open dry habitats such as urban areas around San Jose and seasonally dry habitats of Guanacaste Province. I have records of the species from Santa Rosa National Park, Palo Verde, San Jose, and as far south as Quepos, but I never collected any Acromyrmex in the wet forest of the Osa Peninsula during extensive collecting there in the 1980's.
On the nature trail near the headquarters of Santa Rosa National Park I once observed workers carrying cut flower parts up a tree, suggesting that nests may occasionally be arboreal.
Queens multiply mate, and colonies are facultatively polygynous (Bekkevold et al. 1999).
Bekkevold, D., J. Frydenberg, and J. J. Boomsma. 1999. Multiple mating and facultative polygyny in the Panamanian leafcutter ant Acromyrmex echinatior. Behavioral Ecology and Sociobiology 46:103-109.
Schultz, T. R., D. Bekkevold, and J. J. Boomsma. 1998. Acromyrmex insinuator new species: an incipient social parasite of fungus-growing ants. Insectes Sociaux 45:457-471.
Found most commonly in these habitats: 10 times found in lowland wet forest, 6 times found in 2º lowland rainforest, 3 times found in 2º wet forest, 3 times found in tropical rainforest, 2 times found in mesophil forest, 2 times found in ridgetop cloud forest, 2 times found in tropical moist forest, 1 times found in montane rainforest, 1 times found in scrubby xeric vegetation, 1 times found in 2nd growth dry forest, ...
Collected most commonly using these methods or in the following microhabitats: 17 times Baiting, 8 times search, 6 times Beating, 3 times Malaise, 1 times light, 1 times MaxiWinkler, 1 times MiniWinkler
Elevations: collected from 10 - 1700 meters, 300 meters average