THE PARASITIC TURBELLARIAN URASTOMA CYPRINAE (PLATYHELMINTHES, URASTOMIDAE) FROM BLUE MUSSEL MYTILUS-GALLOPROVINCIALIS IN SPAIN - OCCURRENCE AND PATHOLOGY

The turbellarian Urastoma cyprinae (Graff, 1882) Graff, 1903 was found inhabiting the mantle cavity between the lamellae of the demibranchs of mussels Mytilus galloprovincialis Lamarck cultured in Galicia (NW S pain). Heavily infested mussels were recognized by the presence of whi te spots in the gills. The affected area exhibited disarrangement of t he gill filaments. The space between 2 lamellae was considerably reduc ed and the blood sinuses were wider in the unhealthy area than in the healthy area. The turbellarian also induced a heavy infiltration by bl ood cells and subsequent necrosis of the gill tissues. Routine parasit ological studies showed that this parasite was first detected in the G alician region in early 1989. In 1993, U. cyprinae appeared to be pres ent in the 3 main production rias in the Galician region, affecting bo th natural beds and rafted mussels. U. cyprinae could be considered a potential threat to mussel culture.