Abstract
Four species of the muricine subgenus Pterochelus are distributed around the perimeter of the Australian continent in a simple geographic pattern: P. acanthopterus in the north; P. duffusi in the east; P. triformis in the south; and p. westralis in the west. To this number may be added two geographically intermediate species: Pterynotus (Pterochelus) akation, n. sp., in the northwest; and P. (P.) undosus, n. sp., in the southwest The species P. saibaiensis was named from the northeast, but it is here considered to be a synonym of P. acanthopterus, which thus ranges from the Torres Strait to Rottnest Island, W.A.