Language: English with bilingual abstract and identification key in English and French
A taxonomic revision of the genus Noronhia Stadtm. ex Thouars (Oleaceae) in Madagascar and the Comoro Islands is presented. Using results from previous phylogenetic and morphometric analyses along with consideration of potential diagnostic features and ecogeographic characters, 87 species are recognized, 36 of which are described as new, a twofold increase since the last treatment 60 years ago, resulting mainly from new botanical collections accumulated during the last three decades. In addition, three new combinations are proposed and 18 lectotypes are designated. The treatment includes also a synopsis of morphological variation of vegetative and reproductive structures, an identification key to the species as well as distribution maps of all species plus illustrations and field photographs of selected taxa. Preliminary conservation assessments following the IUCN Red List Criteria indicate that 54 species, representing 62% of the total number of species treated here, are threatened, of which five are considered Critically Endangered [CR], 22 Endangered [EN] and 27 Vulnerable [VU]. An evaluation of the biogeographic patterns of Noronhia in Madagascar shows that species richness is higher in mountainous areas of the north and south than elsewhere, supporting the idea that they are centers of diversification of the Malagasy flora as well as fauna. Of the 87 species recognized, 82 are endemic to Madagascar, three occur only in the Comoros, one is shared between Madagascar and the Comoros, and another is shared between the Comoros and Mascarenes.