Italian marine Gastrotricha: III. Four new pentancrous species of the genusTetranchyroderma(Macrodasyida, Thaumastodermatidae)

Of the thaumastodermatid gastrotrichs that were collected in the years 1989–1991, during a faunistic survey of the Italian coasts, several have been placed in the genus Tetranchyroderma. On the basis of their distinctive morphological characters, four that bear pentancres are being described as new species, three with a complete dorsal covering of ancres: T. kontosomum, T. polyprobo‐lostomum, T. tanymesatherum, and one with an incomplete covering: T. anomalopsum.