Résumé
Melanopsidium is a poorly known monospecific genus, represented by dioecious shrubs endemic to Brazilian restingas. Its systematic relationships have been considered ambiguous by some authors, but recent phylogenetic studies strongly support its position in the tribe Gardenieae, and more precisely within the "Alibertia-group." Its complex taxonomic history, full description, lectotypification, synonymy, and biogeographic observations are presented; original plates here selected as lectotypes are reproduced; staminate and pistillate flowers are illustrated; and a distribution map is included.