Melanopsidium Colla (Rubiaceae, Gardenieae): a monospecific Brazilian genus with a complex nomenclatural history

Melanopsidium is a poorly known monospecific ge nus, represented by dioecio us 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 descripti on, lectotypification, synonymy, and biogeographic observations are present ed; original plates here selected as lectotypes are reproduced; staminate a nd pistillate flowers are illustrated; and a distribution map is included.