Life cycle and morphology of Metagonimus miyatai (Digenea: Heterophyidae) from Nagano, Japan.

The life cycle of Metagonimus miyatai Saito, Chai, Kim, Lee and Rim, 1997 (Digenea: Heterophyidae) was studied in the Hiroi River at Kotobuki, Iiyama City, Nagano Prefecture, central Japan. Daughter rediae and cercariae were found in Semisulcospira libertina (Gould) and S. dolorosa (Gould) (Gastropoda: Pleuroceridae). Metacercariae were found encysted in Phoxinus lagowskii steindachneri Sauvage (Osteichthyes: Cyprinidae). Cercariae were experimentally exposed to P. lagowskii steindachneri, and metacercariae were obtained from the fish. Metacercariae of natural and experimental infections were experimentally fed to respective golden hamsters, and gravid adults identifiable as M. miyatai were recovered from the small intestine of the golden hamsters. The daughter redia, cercaria, metacercariae and adults are described. The life cycle of M. miyatai is discussed.