A taxonomic synopsis of unifoliolate continental African Vepris (Rutaceae) with three new threatened forest tree species from Kenya and Tanzania

Descriptions and illustrations are presented for three new species to science, Vepris udzungwa Cheek, V. lukei Cheek (both Udzungwa Mts, Tanzania) and V. robertsoniae Cheek & Q. Luke (SE Kenyan kaya forests) in the context of a synoptic taxonomic revision, with an identification key to all the known unifoliolate taxa of Vepris in continental Africa. The remaining species are given skeletal taxonomic treatments (lacking descriptions). One widespread species in montane eastern Africa is renamed as Vepris simplex Cheek because its previous name, Vepris simplicifolia (Engl.)Mziray is predated by Vepris simplicifolia Endl. (basionym of Sarcomelicope simplicifolia (Endl.)T.G. Hartley, a widespread species of Australia, Lord Howe and Norfolk Islands, and of New Caledonia). Conservation assessments are presented for all species, or provisional conservation assessments are presented. Of the 13 taxa, 11 are considered threatened, of which six are VU, two EN and three CR, of which two are possibly extinct globally in the Uluguru Mts of Tanzania although not yet Red Listed on iucnredlist.org.