A study of morphological variation in Ryparosa javanica (Blume) Kurz ex Koord. & Valeton sensu lato (Achariaceae; Flacourtiaceae pro parte) was undertaken after distinct differences were observed between Australian and Bornean populations. The confusing taxonomic history of R. javanica is first summarised. Phenetic techniques of agglomerative classification and ordination were used to analyse herbarium and field-collected specimens. Distinct groupings based on vegetative characters were supported by reproductive traits, plant architecture, ant?plant associations and geographical discontinuities. This work demonstrates that the current circumscription of R. javanica is a complex of at least nine species: R. javanica sensu stricto now confined to Sumatra, Java and Bali; three species that warrant reinstatement: R. amplifolia (K.Sch.) Mildbr. from New Guinea, R. kurzii King from the Andaman and Nicobar Islands and R. wrayi King from southern Myanmar and Thailand, the Malay Peninsula and northern Sumatra; and five new species described as R. maculata B.L.Webber from eastern New Guinea, R. anterides B.L.Webber from eastern Borneo, R. milleri B.L.Webber from New Guinea, R. maycockii B.L.Webber from western Borneo and R. kurrangii B.L.Webber from northern Australia. A key to the species and commonly mistaken taxa is provided.