Abstract
Notocotylus tadornae n.sp. is described from the New Zealand paradise shelduck Tadorna variegata (Gmelin), and Notocotylus gippyensis (Beverley-Burton, 1958), is recorded from three waterfowl species in New Zealand. The life histories of both species are shown to involve an hydrobiid snail Potamopyrgus antipodarum, as intermediate host. The taxonomic affiliations of N. tadornae and N. gippyensis are discussed.