Revision of the genus Aristolochia (Aristolochiaceae) in Africa, Madagascar and adjacent islands

Abstract

A taxonomic revision of the genus Aristolochia in Africa, Madagascar, the West African islands, the Comores and the Mascarenes is presented. In total, 11 indigenous species are accepted: A. albida, baetica, bracteolata, embergeri, heppi, hockii, fontanesii, paucinervis, pistolochia, rigida and sempervirens. Descriptions, distribution maps and a complete taxonomic synonymy are presented. The investigation revealed three clades: (1) A group from northern Africa, including the West African islands (A. baetica, A. sempervirens, A. fontanesii, A. pistolochia, A. paucinervis). Those taxa are characterized by unilabiate flowers with a sessile utricle. (2) A group from central and East Africa as well as Madagascar and adjacent islands. Those plants also have unilabiate flowers, but with a stiped utricle (A. bracteolata, A. albida, A. embergeri, A. heppii and A. hockii). The latter four species are endemic to the region. (3) A single species restricted to Somalia (A. rigida). Its flower characters do not match those of the remaining African species. The flower is trumpet-like and bilabiate, resembling species from the Near East. These relationships are also supported by the molecular analysis of the trnL–F region.