New results from phylogenetic analyses utilizing chloroplast and nuclear DNA markers agree with morphology in support of the unification of all of Rheedia L. and part of Ochrocarpos Thouars with Garcinia L. and show that species occurring in Madagascar and the Comoros fall into four separate lineages, which are designated here as informal species groups. An examination of Garcinia from these areas results in the recognition of 32 currently described species, all but one of which are endemic. The widespread African species, G. livingstonei T. Anderson, is noted for the first time to occur in Mayotte. Eleven new combinations are published here: G. ambrensis (H. Perrier) P. Sweeney & Z. S. Rogers, G. anjouanensis (H. Perrier) P. Sweeney & Z. S. Rogers, G. arenicola (Jumelle & H. Perrier) P. Sweeney & Z. S. Rogers, G. calcicola (Jumelle & H. Perrier) P. Sweeney & Z. S. Rogers, G. dalleizettei (H. Perrier) P. Sweeney & Z. S. Rogers, G. mangorensis (R. Viguier & Humbert) P. Sweeney & Z. S. Rogers, G. multifida (H. Perrier) P. Sweeney & Z. S. Rogers, G. parvula (H. Perrier) P. Sweeney & Z. S. Rogers, G. thouvenotii (H. Perrier) P. Sweeney & Z. S. Rogers, G. tsaratananensis (H. Perrier) P. Sweeney & Z. S. Rogers), and G. urschii (H. Perrier) P. Sweeney & Z. S. Rogers. Three new names, G. dauphinensis P. Sweeney & Z. S. Rogers, G. megistophylla P. Sweeney & Z. S. Rogers, and G. tsimatimia P. Sweeney & Z. S. Rogers, are provided for O. parvifolius Scott-Elliot, R. megaphylla H. Perrier, and R. pedicellata (Jumelle & H. Perrier) H. Perrier, respectively. Lectotypes are designated for 12 names: G. crassiflora Jumelle & H. Perrier, G. disepala Vesque, G. melleri Baker, G. polyphlebia Baker, G. verrucosa Jumelle & H. Perrier, O. ambrensis H. Perrier, O. macrophyllus O. Hoffmann, O. parvifolius, O. parvulus H. Perrier, O. tsaratananae H. Perrier, R. arenicola Jumelle & H. Perrier, and R. calcicola Jumelle & H. Perrier.