African violets, the genus Saintpaulia H. Wendl., are restricted to the Eastern Arc Mountains and the coastal lowlands of East Africa. The 24 described taxa of Saintpaulia are all narrowly distributed and rare, and loss of their natural habitats is a major threat to their future survival. Species delimitation within the genus has proven to be difficult, and no modern taxonomic revision exists post Burtt (1958, 1964). Hence, problems arise when efforts are made to determine conservation priorities. This study has examined phylogenetic relationships within Saintpaulia based on nuclear 5S-NTS ribosomal DNA sequences. The most-parsimonious and bootstrap consensus trees (using Streptocarpus spp. as outgroups) support the basal position of the Saintpaulia pusilla and S. goetzeana clade from the Uluguru Mts., Tanzania, which could indicate an origin of Saintpaulia there. The Teita Hills (Kenya) are the next most basal area, followed by the Nguru Mts., which are sister to the Usambaras plus lowland sites. Branch lengths are uniformly long among and within the Uluguru, Teita, and Nguru clades, which contrasts with the rather short branches seen in the highly polytomous Usambaras-lowland clade. The biogeographic and sequence divergence patterns suggest that the basal Saintpaulia species may be relicts from formerly larger populations that may have existed when forests were continuous. The more recent radiation in the Usambara Mts. and costal lowlands may also show relictual distribution patterns through the influence of climatic or human-induced vegetational change. Also indicated is that the basal clades (Ulugurus, Teita, and Ngurus) hold the vast majority of genetic variation in the genus, and these may therefore warrant the greatest priority for conservation efforts. This research is funded by the Center for Tropical Biodiversity (Denmark) and the Lewis B. and Dorothy Cullman Foundation.

Key words: biogeography, conservation, Eastern Arc Mountains, Gesneriaceae, molecular systematics, Saintpaulia