Taxonomic revision and phylogenetic relationships of Thinouia (Sapindaceae), a neotropical genus

A taxonomic revision of <i>Thinouia</i> (Sapindaceae) is presented, including typification and descriptions for all accepted species. Phylogenetic analyses based on molecular data confirm that the genus is monophyletic and suggest two main clades with <i>T.cazumbensis</i> sister to the other species of the genus. Thirteen species of <i>Thinouia</i> are accepted, including a new species from Amazonia. The genus is distributed across continental tropical America, with its highest diversity found in South America. Its species can be distinguished by morphological details of leaves, indumentum, inflorescences, flowers, and fruits. We present a comprehensive review of the morphology and geographical distribution of the genus, along with an identification key, distribution maps, conservation risk assessments, illustrations, and comments on the ecology and taxonomy for all species, gathered from the literature and fieldwork.