Abstract: | SYNOPSIS. A new species of neogregarine, Mattesia geminata sp. n., that infects immature stages of the tropical fire ant, Solenopsis geminata (Fabricius), is described. The parasite, which develops in the hypodermis, causes disruption of the developing eyes, melanization of the cuticle, and death of pupae. lntracolonial infection rates are usually less than 2±, but may exceed 90±. Attempts to transmit the infection were unsuccessful. |