A taxonomic revision of the Neotropical genus Cremastosperma (Annonaceae), including five new species.

We present a taxonomic revision of Cremastosperma, a genus of Neotropical Annonaceae occurring in lowland to premontane wet forest, mostly in areas surrounding the Andean mountain chain. We recognise 34 species, describing five as new here: from east of the Andes, C.brachypodum Pirie & Chatrou, sp. nov. and C.dolichopodum Pirie & Maas, sp. nov., endemic to Peru; C.confusum Pirie, sp. nov., from southern Peru and adjacent Bolivia and Brazil; and C.alticola Pirie & Chatrou, sp. nov., at higher elevations in northern Peru and Ecuador; and from west of the Andes, C.osicola Pirie & Chatrou, sp. nov. endemic to Costa Rica, the most northerly distributed species of the genus. We provide an identification key, document diagnostic characters and distributions and provide illustrations and extensive lists of specimens, also presenting the latter in the form of mapping data with embedded links to images available online. Of the 34 species, 22 are regional endemics. On the basis of the extent of occurrence and area of occupancy of species estimated from the distribution data, we designate IUCN threat categries for all species. Fourteen species proved to be endangered (EN) and a further one critically endangered (CR), reflecting their rarity and narrow known distributions.