Revision of the African genus Crotonogyne (Euphorbiaceae)

Abstract

Background and aims – The African genus Crotonogyne is revised for the first time since 1912. Identification of new material collected since proved to be very difficult. The revision serves also as a basis for the treatment of the genus in the Flore du Gabon. Methods – Normal practices of herbarium taxonomy have been applied to study the relevant herbarium material available, mainly from BM, BR, BRLU, HBG, K, MA, P, and WAG. The relevant collecting data are stored in the Naturalis Biodiversity Center, Leiden, Section Botany. MAPMAKER was used to produce the distribution maps. Key results – Eleven species are recognised including two new species: Crotonogyne micrantha from Cameroon and C. neglecta from Nigeria, Cameroon, and Equatorial Guinea (Rio Muni). Crotonogyne manniana subsp. congolensis is raised to specific rank. All species, except for C. congolensis with one collection from Angola, are confined tot the Guineo-Congolian region. A full taxonomic treatment with key to the species is given. Male and female flowers of most species are depicted. The distributions of the species are mapped. The flowers are unisexual, but it is not clear whether the species are monoecious or dioecious. Crotonogyne poggei and C. impedita are neotypified and C. angustifolia, C. gabunensis, C. lasiocarpa, C. ledermanniana, C. manniana, C. preussii, C. strigosa, and C. zenkeri are lectotypified.