A new species of strongyloid nematode from the genus Cloacina (Chabertiidae: Cloacininae) is described from the stomach of the hill kangaroo or euro (Macropus robustus) (Marsupialia: Macropodidae) from Western Australia. Cloacina atthis sp. nov. was found only in euros from the Pilbara region in the northwest of Western Australia, in spite of extensive collecting of the same host species from around the Australian continent. C. atthis is most closely related to Cloacina clymene, a species found in the same host species but only in the eastern half of the continent; the two species differ in minor morphological features (the shape of the wall of the buccal capsule, spicule lengths, the degree of sclerotisation of the gubernaculum and the shape of the vagina) as well as in differences in the internal transcribed spacers of ribosomal DNA. This study highlights the importance of using molecular methods when investigating the apparently disjunct distributions of strongyloid nematodes.