THE LIFE-CYCLE OF PARYPHOSTOMUM-RADIATUM (DUJARDIN, 1845) (TREMATODA,ECHINOSTOMATIDAE), A PARASITE OF CORMORANTS

The life cycle of the trematode Paryphostomum radiatum (Dujardin, 1845 ), parasitizing cormorants (Phalacrocoracidae), was studied under both natural and laboratory conditions. Snails Gyraulus albus and Segmenti na nitida were recorded for the first time as first intermediate hosts of P. radiatum in natural conditions. Bathyomphalus contortus and Ani sus leucostomus, experimentally infected with P. radiatum miracidia, a nd fish Scardinius erythrophthalmus, Tinca tinca, Gobio gobio, Alburno ides bipunctatus, Blicca bjoerkna, Cyprinus carpio, Noemacheilus barba tulus, Perca fluviatilis, and Lebistes reticulatus, infected with cerc ariae of P. radiatum, were found as the first and second intermediate hosts under laboratory conditions, respectively. With the exception of the sporocyst, all developmental stages are described and illustrated , including scanning electron photomicrographs of rediae and cercariae .