First occurrence of Schistosomatidae infecting Aplexa hypnorum (Gastropoda, Physidae) in France.

Due to the recrudescence of cercarial dermatitis in the world, larval Schistosomatidae have been researched during 20 months in gastropods of stagnant fresh waters in a wetland. Brevifurcate ocellate cercariae have been detected after crushing in a species of Physidae, Aplexa hypnorum, with a prevalence of 6.52%. Up to now, this species had never been found infected by larval trematodes. Lymnaeidae, Planorbidae and other Physidae didn't harbour schistosomatids. Cercariae of A. hypnorum present furcal fin-folds and the length of the tail stem is inferior to that of the body. Only cercariae of Heterobilharzia americana, Schistosomatidae of Carnivora in America, have also these two features. This species, not described in Physidae, is an agent of the human cercarial dermatitis. Schistosomatid cercariae in american species of Physidae have been compared with that of A. hypnorum. Brevifurcate ocellate cercariae of A. hypnorum, possible agent of the cercarial dematitis, probably belong to a new species with unknown genus.