Tetraphyllidean cysticerci in the peritoneal cavity of the common dolphin

Cysticerci of the cestodes Monorygma grimaldii and Phyllobothrium delphini were encountered during necropsy of an adult common dolphin (Delphinus delphis) found dead on the southeastern coast of Australia. Monorygma grimaldii cysticerci were found within highly organized retroperitoneal cysts, whereas P. delphini cysticerci in the subcutaneous blubber did not occupy specialized structures. There was a localized lymphoplasmacytic host response to the presence of cysticerci of both species, but M. grimaldii provoked a more severe suppurative response than P. delphini. The systematics and life history of both parasites are incompletely known, but sharks postulated as the potential definitive hosts are found in the region. A unique cysticercus of M. grimaldii was found lying free in the peritoneal cavity of this dolphin. Two rare records of M. grimaldii cysticerci in pinnipeds from the literature include one case of aberrant migration to the testis.