Gastrotricha from Italian brackish water environments with the descriptionof a new species of Chaetonotus

During 1996-1997 a systematic sampling programme was carried out in brackis h coastal lakes and lagoons and in the delta of the River Po. In six of the nine collecting locations, 12 species of Gastrotricha were identified. One species, Chaetonotus ichthydioides, is new to science; another three speci es, the chaetonotidans Heterolepidoderma foliatum and the macrodasyidans De ndrodasys ponticus and Turbanella cf. pontica, and one macrodasyidan genus, Paradasys (P. subterraneus), were found in Italy for the first time. The u nusual morphology of some of the species identified shows that Gastrotricha colonized brackish waters from both marine and freshwater habitats.