A taxonomic revision of the genus amaracarpus (Rubiaceae, Psychotrieae)

A taxonomic revision of Amaracarpus Blume (Rubiaceae, Psychotrieae) is presented. The salient characteristics of Amaracarpus are given, with particular attention to the differences between Amaracarpus, Dolianthus and Psychotria. The taxonomic account includes a key to species, an informal (artificial) subgeneric classification, full descriptions, and a list of specimens examined. Amaracarpus comprises 22 species: six new combinations are proposed, one new species is described, eight species are moved to other genera, the transfer of 12 species to Psychotria is confirmed, and numerous taxa are placed into synonymy. A checklist of all Amaracarpus names is provided.