Megalomyrmex wettereri is a Neotropical species of ants in the subfamily Myrmicinae.

Megalomyrmex wettereri is known from two lowland rainforest sites: Barro Colorado Island in Panama and La Selva Biological Station in Costa Rica.

Colonies of M. wettereri were found occupying abandoned nests of Cyphomyrmex longiscapus.

The fungus gardens of the Cyphomyrmex were intact and the Megalomyrmex workers were observed feeding on the fungal symbiont.

Adams et al. (2000) concluded that M. wettereri was an "agro-predator," raiding Cyphomyrmex colonies en masse, displacing the Cyphomyrmex workers, and feeding on the remaining brood and fungi.