Melicope balgooyi, a new species of Melicope (Rutaceae) is described. It is known only from the Austral Islands in the South Pacific (French Polynesia). However, it is not closely related to the other two species previously known from the Austral Islands, which are part of Melicope section Vitiflorae. The new species belongs to Melicope section Melicope and is most closely related to species from New Zealand, the Kermadec Islands, and the Society Islands. The new species has alternate to sub-opposite leaves, which is a very rare arrangement in Melicope and has only been described for two other species of the genus so far.
Keywords: Austral Islands; Bass Islands; French Polynesia; IUCN Red List Category; Melicope; Pacific biogeography; Rapa Iti; Rutaceae.