[Phyletic affinities among Polystomatidae (Monogenea)].

The chaetotaxy and ciliated cells in two Monogenean larvae of marine fishes are described for the first time: a Monopisthocotylea Diplectanum aequans (Wagener, 1857) Diesing, 1858 parasite of Dicentrarchus Labrax (L) and a Polyopisthocotylea, Microcotyle mormyri Lorenz, 1878 parasite of Pagellus mormyrus (L). A comparative study with the known larvae shows evidence of two larval types in the Monogenea of fishes, related to the two great phyla of the class: the Monopisthocoytylea and Polyopisthocotylea. The Polystomatidae, Monogenea from Amphibia and Chelonia, belong to the Polyopisthocotylea on account of their larval chaetotaxy. But the proximity of the Polystomatidae with the Tetraonchidae, within the Polyonchoinea Bychowsky, 1975 is not confirmed.