Digenean metacercariae (Timoniellaspp.,Labratrema minimusandCryptocotyle concava) from the flounder,platichthys flesus, in the tidal Thames

Abstract

A detailed examination of the abundant flatfish speciesPlatichthys flesus, the flounder, in the tidal Thames has revealed the presence of four digenean metacercarial parasites,Cryptocotyle concava(Creplin, 1825),Timoniella imbutiforme(Molin, 1859),T. praeterita(Looss, 1901) andLabratrema minimus(Stossich, 1887). Flounders were recorded as a new second intermediate host forT. praeteritaandL. minimus. They were also recorded as second intermediate hosts for the first time in British waters forT. imbutiforme. The temporal and spatial characteristics of these infections were examined and were believed to provide indirect parasitological evidence of the movement patterns of flounders during their utilization of the Thames Estuary as a nursery ground. From these data it was also surmised that the first intermediate host ofT. imbutiforme,T. praeteritaandC. concavawas probably the molluscan speciesHydrobia ulvaein the lower Thames Estuary, whereasL. minimuswas most likely to occur in the molluscan hostCerastoderma edule, also present in the lower estuary.