Pseudohexabothrium taeniurae n. sp. is proposed for a hexabothriid monogenean found on the gills of Taeniura lymma (Forsskål) off Heron Island, Great Barrier Reef, Queensland, Australia. Pseudohexabothrium taeniurae is distinguished from Pseudohexabothrium rajae Brinkmann, 1952, the type and only species of the genus, by the morphology of the sucker sclerites and eggs, and by the size of the hamuli, pharynx, and the "false" oral sucker. The generic diagnosis of Pseudohexabothrium is revised. A phylogenetic analysis places Pseudohexabothrium as the sister group to the rest of the family except Hexabothrium.