Temporal variations in the infection of a population of Clypeomorus bifasciata (Gastropoda: Prosobranchia) by a digenean microphallid larva in Kuwait Bay.

The prosobranch snail Clypeomorus bifasciata in Kuwait Bay was examined for digenean infections over a one year period during 1994/1995. A total of 1500 snails was examined and 567 (37.8%) were found to harbour nine digenean species. The prevalence of a microphallid species was 33.9% while each of the others occurred in less than 1.2% of the snails. The prevalence of infection increased with shell size. Multiple infections were observed in only five of the infected snails and the microphallid was involved in all of them. Snails were infected with the microphallid throughout the year and there appeared to be two peaks in the proportion of infected snails shedding cercariae, a winter peak from November to January and a summer peak from June to August. The crab Xantho exaratus collected from snail sampling sites was heavily parasitized by microphallid metacercariae of the genera Longiductotrema and Microphallus. This is the first report on microphallid metacercariae in crabs in the Arabian Gulf region.