In the light of morphological and molecular evidence that the genus Mascagnia is polyphyletic, eight segregate genera are described, discussed, and illustrated, the necessary new combinations are proposed, and five new species are described (Amorimia camporum, A. kariniana, A. septentrionalis, A. velutina, and Niedenzuella caracasana). Keys to genera and species are provided. The genera and species are: Adelphia W. R. Anderson [A. hiraea (Gaertner) W. R. Anderson, A. macrophylla (Rusby) W. R. Anderson, A. mirabilis (W. R. Anderson) W. R. Anderson, A. platyrachis (Triana & Planchon) W. R. Anderson]; Aenigmatanthera W. R. Anderson [A. doniana (Grisebach in Martius) W. R. Anderson, A. lasiandra (A. Jussieu) W. R. Anderson]; Alicia W. R. Anderson [A. anisopetala (A. Jussieu in A. St.-Hilaire) W. R. Anderson, A. macrodisca (Triana & Planchon) W. R. Anderson]; Amorimia W. R. Anderson [A. amazonica (Niedenzu) W. R. Anderson, A. camporum W. R. Anderson, A. concinna (C. V. Morton) W. R. Anderson, A. exotropica (Grisebach in Martius) W. R. Anderson, A. kariniana W. R. Anderson, A. maritima (A. Jussieu) W. R. Anderson, A. pubiflora (A. Jussieu in A. St.-Hilaire) W. R. Anderson, A. rigida (A. Jussieu in A. St.-Hilaire) W. R. Anderson, A. septentrionalis W. R. Anderson, A. velutina W. R. Anderson]; Carolus W. R. Anderson [C. anderssonii (W. R. Anderson) W. R. Anderson, C. chasei (W. R. Anderson) W. R. Anderson, C. chlorocarpus (A. Jussieu) W. R. Anderson, C. dukei (Cuatrecasas & Croat) W. R. Anderson, C. renidens (A. Jussieu) W. R. Anderson, C. sinemariensis (Aublet) W. R. Anderson]; Christianella W. R. Anderson [C. glandulifera (Cuatrecasas) W. R. Anderson, C. mesoamericana (W. R. Anderson) W. R. Anderson, C. multiglandulosa (Niedenzu in Chodat & Hassler) W. R. Anderson, C. paludicola (W. R. Anderson) W. R. Anderson, C. surinamensis (Kostermans) W. R. Anderson]; Malpighiodes Niedenzu [M. bracteosa (Grisebach in Martius) W. R. Anderson, M. guianensis (W. R. Anderson) W. R. Anderson, M. leucanthele (Grisebach in Martius) W. R. Anderson, M. liesneri (W. R. Anderson) W. R. Anderson]; and Niedenzuella W. R. Anderson [N. acutifolia (Cavanilles) W. R. Anderson, N. caracasana W. R. Anderson, N. castanea (Cuatrecasas) W. R. Anderson, N. glabra (Sprengel) W.