Notocotylidae (Digenea) from the Australian water rat Hydromys chrysogaster Geoffroy, 1804 (Muridae)

Notocotylus johnstoni n. sp., N. imbricatus (Looss, 1893) Szidat, 1935 and Catatropis nicolli n. sp. are described from the large intestine and caecum of the Australian water rat Hydromys chrysogaster (Rodentia: Muridae). The water rat is the only known mammalian host of notocotylids in Australia. N. imbricatus, recorded from Tasmania, is a cosmopolitan species which elsewhere uses birds and bithyniid snails as definitive and intermediate hosts respectively. In Tasmania bithyniid snails are unknown and the only known definitive host is a mammal. In view of this it is possible that the material examined represents a species distinct from N. imbricatus. Catatropis gallinulae Johnston, 1928 is found to have three rows of ventral papillae and thus to belong to the genus Notocotylus. The new combination Notocotylus gallinulae (Johnston, 1928) is a senior homonym of Notocotylus gallinulae El-Naffar & Khalifa, 1983 which is replaced with Notocotylus elnaffari nom. nov.