The enigmatic genus Rhopalobrachium from New Caledonia is proposed as a synonym of the Pacific genus Cyclophyllum, in the tribe Vanguerieae. Recent fieldwork has resulted in new material and field observations that were used in conjunction with herbarium material to examine the morphology and ecology of Rhopalobrachium fragrans. Based on these data, a new combination, Cyclophyllum fragans, was proposed. A lectotype was chosen and a species description and a bibliographic review are included. Following the IUCN criteria, Cyclophyllum fragrans is considered endangered.