Six New Species of Euphorbia (Subgenus Esula) from Ethiopia

Abstract

Recent Flora of Ethiopia collecting trips in southern Ethiopia have produced a wealth of material of Euphorbia including what appear to be a number of new species belonging to several distinct groups within the genus. The genus is almost certainly the largest within the Ethiopian Flora with 99 native species at the latest count. Several further species are recorded from just outside Ethiopia which, coupled with the apparent abundance of very local species within the Somali-Masai region of North East Africa, suggests that the final count will be substantially over 100. (Crotalaria (Leguminosae) with some 86 species (Thulin 1982) was hitherto thought to be the best represented genus in the Flora area). Five new species have already been described (Carter & Gilbert 1987; Gilbert & Carter 1984; Gilbert 1987). Gilbert (1987) gives an outline of the major divisions recognised by the author for the genus in Africa; all the species described here belong to subgenus Esula. Subgenus Esula is the largest in the genus and includes a number of sections that are sometimes themselves treated as subgenera (e.g. Carter 1988). This includes Trichadenia and Lyciopsis referred to here. The author has chosen not to follow such a course because it would detract from the more important divisions between the subgenera that are recognised. The new species are all known only from very restricted areas, in some cases single collections, but they are so distinctive and/or belong to relatively well known groups that it seems justified to give them formal names. A number of succulent species belonging to subgenus Euphorbia remain to be described.