Australian beachworms, recognized by specialists as one species Onuphis teves (Ehlers 1868), and by fishermen as a number of forms, were studied to determine whether more than one species was involved. Monthly sampling at a study site (Narrabeen, New South Wales) and collections from other localities were undertaken to study the morphology of beachworms, electrophoretic mobility of glucosephosphate isomerase and aspects of their life history. Three forms of beachworms-slimy, stumpy and kingworm-occur at the study site. Stumpies were found to be young kingworms, while slimy represents a separate species. The two species belong to Americonuphis Orensanz, 1974; the name is preoccupied and is replaced with Australonuphis. The holotype of A. teres is a kingworm and the closely related slimy is described as A. parateres, sp. nov. Four other forms of beachworms were collected from northern New South Wales and Queensland: Stripey, giant, wiry and white-headed wiry. These forms are referred to Onuphis. Stripey and giant are morphologically distinct and are described as O. taeniata, sp. nov., and O. gygis, sp. nov., respectively. Wiry and white-headed wiry belong to a polymorphic species described as O. mariahirsuta, sp. nov.