Abstract: | Oocysts of Calyptospora empristica n. sp., the second described species in its genus, are described from the freshwater starhead topminnow, Fundulus notti, in southern Mississippi. Oocysts are 22 μm in diameter with a wall about 20 nm thick and have no residuum, micropyle, or polar granule. Sporocysts are spheroid, 9 × 5 μm with a two-layered wall approximately 120 nm thick. They have an oblong apical opening at the anterior pole, a single ornamented sporopodium approximately 5.7 μm long at the posterior pole, and a residuum. An intermediate host, most likely the freshwater grass shrimp Palaemonetes kadiakensis, is probably required to complete the life cycle. |