A new species of Acanthocotyle Monticelli, 1888 (Platyhelminthes: Monogenea: Acanthocotylidae) from the ventral skin of the banded stingaree, Urolophus cruciatus (Lacépède, 1804), from Tasmania, Australia.

Acanthocotyle urolophi sp. nov. is described from the skin of the banded stingaree, Urolophus cruciatus (Lacépède, 1804). This is the first acanthocotylid to be described from Australian waters. Acanthocotyle urolophi sp. nov. is distinguished from other species of Acanthocotyle by a combination of the number of vitelline follicles 38 (33-46) and the number of rows 35 (32-37) of sclerites on the pseudohaptor. In addition, Acanthocotyle urolophi sp. nov. has no germarial appendix and no uterine "arm". A uterine receptaculum seminis was not identified in whole mounts. There is no penis papilla and no penis sclerite associated with the male reproductive opening. A brief description of the larva is provided. The diagnosis of the Acanthocotylidae Price, 1936 is amended and we review the Allacanthocotylinae Yamaguti, 1963, Lophocotylinae Yamaguti, 1963 and Pseudacanthocotylinae Yamaguti, 1963. We deem that these subfamilies are invalid and that the family now comprises only the subfamily Acanthocotylinae and the genus Acanthocotyle. The validity of species previously assigned to the Acanthocotylidae (sensu Yamaguti, 1963) is discussed and a key to what we consider to be the valid species in the family is also provided.