A taxonomic revision of the reinstated genus Leplaea and the newly recognized genus Neoguarea (Meliaceae, Sapindales): the exclusion of Guarea from Africa

Background and aims - The taxonomy of the African representatives of the genus Guarea, among them a number of timber species, is badly understood. The group is revised. Methods - Standard herbarium taxonomy practices were used. Specimens from fifteen different herbaria were studied. Using a GIS application and geo-referenced herbarium specimens, IUCN Red List categories are assessed for each species. Key results - Morphological studies show that the group is distinct from the South-American members of Guarea and deserves generic status. This is supported by molecular data. Therefore the genus Leplaea is reinstated to accommodate five of the species formerly placed in Guarea and the new combinations are presented. Furthermore, two new species, L. adenopunctata E.J.M.Koenen & J.J.de Wilde and L. cauliflora E.J.M.Koenen & J.J.de Wilde are formally described. In addition to de Wilde's (2007) revision of Heckeldora, one more species, G. leonensis, is transferred to this genus and the new combination made. G. glomerulata is shown to be morphologically distinct and to deserve generic status as well. This is endorsed by molecular data. As a consequence, Guarea sect. Neoguarea Harms is granted generic rank to accommodate this species; the new genus is described and the new combination made. A generic key to the African Guareeae is provided, as well as a key to the species of Leplaea; botanical drawings, distribution maps and IUCN Red List categories are presented.