Revisions of Pterogastra and Schwackaea (Melastomataceae: Melastomeae)

The closely related neotropical melastomean genera Pterogastra and Schwackaea are revised, the species illustrated, and their distribution mapped. Schwackaea is maintained as a monotypic genus because it is readily distinguished from all other melastomes by its 8‐winged capsule. This weedy little plant occurs from Mexico throughout Central America, chiefly on the Pacific slope, to northern Colombia and on Cocos Island and grows in natural or man‐made savannas from sealevel to 2000 m altitude. Two species are recognized in Pterogastra and one new combination, P. divaricata spp. glabra, is made. Pterogastra is characterized by distinctly 4‐ or 5‐winged capsules, unlike those of Schwackaea or any other New World melastome. The more widespread species occurs in Colombia, Venezuela, Guyana, Ecuador, and Peru at altitudes between sealevel and 2600 m in natural or disturbed grasslands. The second species is endemic in southwestern Venezuela and is confined to natural savannas at low altitudes.