Cercaria anadarae Sp. N. parasitizing a bivalve mollusc, Anadara brasiliana (Lamarck), from the Northwest Gulf of Mexico

Cercaria anadarae sp. n., a cytophorus cercaria of a digenetic trematode of the superfamily Hemiuroidea, was found developing in the nephridia of 39 to 356 specimens of Anadar brasiliana (Lamarck), the incongruous ark clam, collected from the beachfront in the vicinity of Galveston, Texas. The germinal sacs containing cercariae were found to leave the host clam before liberation of cercariae when clams were isolated in bowls of seawater. This is the first record of a hemiuroid larva from a bivalve host, all previous hemiuroid having been reported from gastropod molluscs.