A Revision of Neotropical <i>Bonyunia</i> (Loganiaceae: Antonieae)

A revision of the Neotropical genus <i>Bonyunia</i> M. R. Schomb. ex Progel (Loganiaceae, Antonieae) is provided, including a key to species, description, distribution, IUCN Red List status, and discussion. <i>Bonyunia</i> is morphologically and ecologically diverse with taxonomically informative characters that include habit, seed and leaf morphology, and the shape and indument of the calyx, bracts, and bracteoles. <i>Bonyunia</i> occurs in lowland regions of the Amazon River watershed (Brazil and Bolivia), the Orinoco River watershed (Colombia and Venezuela), tepuis of the Guayana region and outliers (Brazil, Guyana, Venezuela, and Colombia), and lowland regions of Amazon Basin–facing Andes in Peru, throughout on white sands. Ten species are recognized, including four established species: <i>B. antoniifolia</i> Progel, <i>B. aquatica</i> Ducke, <i>B. minor</i> N. E. Br. (including <i>B. cinchonoides</i> Gleason & Standl.), and <i>B. superba</i> M. R. Schomb. ex Progel. Six species are newly described: <i>B. excelsa</i> J. R. Grant (Colombia), <i>B. magnifica</i> J. R. Grant (Brazil), <i>B. nobilis</i> J. R. Grant (Colombia), <i>B. pulchra</i> Ricketson, J. R. Grant & Liesner (Peru), <i>B. spectabilis</i> J. R. Grant (Guyana), and <i>B. venusta</i> J. R. Grant (Brazil).