AN ASSESSMENT OF LESIONS IN BAY SCALLOPS ARGOPECTEN-IRRADIANS ATTRIBUTED TO PERKINSUS-KARLSSONI (PROTOZOA, APICOMPLEXA)

Lesions found in bay scallops Argopecten irradians imported into Atlan tic Canada for culture were attributed to a parasite Perkinsus karlsso ni. It appears, however, that stages from several organisms were combi ned to create the life cycle of P, karlssoni. The ultrastructure of th e agent in lesions of bay scallops is not documented adequately to dia gnose affinities to the genus Perkinsus. Furthermore, there was discre pancy as to whether P, karlssoni enlarged in fluid thioglycollate medi um, and the shape and structure of the prezoosporangia as well as the movement and life span of the zoospores were not consistent with the g enus Perkinsus. P. karlssoni cannot be considered as a species of Perk insus.