Abstract
A taxonomic study of the Neotropical genus Moutabea (Polygalaceae) in Brazil is presented, based on the analysis of herbarium material and field collections. Nine species are recognized: Moutabea aculeata, M. angustifolia, M. arianiae, M. chodatiana, M. excoriata, M. floribunda, M. gentryi, M. guianensis, and M. victoriana, a new species described here. The Brazilian Amazon is the diversity center of this genus. The following species were considered new occurrences: M. aculeata for the states of Amazonas, Pará and Rondônia; M. angustifolia for Amazonas, Amapá, Pará and Maranhão; M. arianiae for Amazonas, M. chodatiana for Roraima, Amazonas, Amapá and Pará; M. excoriata for Pará and Maranhão; and M. gentryi for Brazil (Amazonas and Rondônia). Moutabea dibotrya is considered synonymous with M. aculeata, and M. silvatica with M. excoriata. Lectotypes for M. dibotrya, M. excoriata and M. silvatica are proposed. An identification key, illustrations and maps of the geographic distributions of the species are presented.