Comparative chaetotaxy of five species of plagiorchiid cercariae, genera Leptophallus, Metaleptophallus, Macrodera and Paralepoderma

The chaetotaxy of five species of plagiorchiid cercariae - Leptophallus nig rovenosus, Metaleptophallus gracillimus, Macrodera longicollis, Paralepoder ma brumpti and P. progeneticum, is described and compared. A great similari ty in the distribution of sensillae in all the species examined, especially in cephalic rings CI-IV, as well as in dorsal and ventral rows, suggests c lose affinities among these species. The variation in the pattern of chaeto taxy observed in P. brumpti and P. progeneticum (presence of 1-3 sensillae of the CI ring inside the oral cavity and numerous sensillae on the ventral sucker) seems to be connected with obligatory progenesis in the life cycle of these species.