SYSTEMATICS, PHYLOGENY, AND BIOGEOGRAPHY OF CHAETOLEPIS (MELASTOMATACEAE).

Cladistic analyses based on morphology were conducted to test for monophyly, estimate the phylogenetic relationships among the taxa of Chaetolepis, and generate the first comprehensive taxonomic revision of the genus. Prior to this study the genus had included species from Andean South America, the Guayana Highlands, Costa Rica, Cuba, and tropical West Africa. As traditionally delimited, Chaetolepis is not monophyletic because the Cuban species, C. cubensis, is more closely related to outgroup species in the genus Tibouchina. Based on discordant morphological characters such as foliar trichome details and seed morphology, C. cubensis is here treated as a Tibouchina, the genus to which it had been transferred by M. Gómez in 1894. Chaetolepis is treated as a monophyletic genus of 11 species distinguished by 4-merous flowers, isomorphic stamens that lack prominent pedoconnectives and appendages, apically setose 4-locular ovary, capsular fruits, and cochleate seeds. Chaetolepis alpina var. latifolia is relegated to synonymy of C. alpina because it lacks consistent distinguishing characters, and C. thymifolia is synonymized under C. anisandra. The West African monotypic genus, Nerophila gentianoides, is tentatively shown to be congeneric with the Central and South American species of Chaetolepis based on morphology. If molecular data confirms this disposition of N. gentianoides by Jacques-Félix, it will become the only genus of Melastomataceae with a trans-Atlantic distribution. A biogeographical analysis based on the phylogenetic results suggests that Chaetolepis originated in the Colombian Andes and possibly the Sierra Nevada de Santa Marta, with independent dispersal events to Costa Rica, Venezuela, and tropical West Africa. [ABSTRACT FROM AUTHOR]