Digenean metacercariae (Timoniella spp., Labratrema minimus and Cryptocotyle concava) from the flounder, platichthys flesus, in the tidal Thames

Abstract

A detailed examination of the abundant flatfish species Platichthys 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) and Labratrema minimus (Stossich, 1887). Flounders were recorded as a new second intermediate host for T. praeterita and L. minimus. They were also recorded as second intermediate hosts for the first time in British waters for T. 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 of T. imbutiforme, T. praeterita and C. concava was probably the molluscan species Hydrobia ulvae in the lower Thames Estuary, whereas L. minimus was most likely to occur in the molluscan host Cerastoderma edule, also present in the lower estuary.