Morphometric data have long suggested the existence of three species of Sicyos in Australia and New Zealand. Molecular data now corroborate this and place the three species in the context of the remaining 72 species of Sicyos, most of them in the New World. We here describe and illustrate Sicyos undara I.Telford & P.Sebastian from northern Queensland and S. mawhai I.Telford & P.Sebastian from New Zealand, and emend the circumscription of S. australis to account for the removal of these two extraneous elements. We also provide a key to the three species, map their ranges, and note their habitat and conservation status.