Barbeya

Abstract: Barbeya is a monotypic genus in the Horn of Africa and adjacent parts of Arabia. It is usually treated as the familyBarbeyaceae and regarded as an aberrant member ofUrticales. Dirachma, with one species on Socotra and one in Somalia, is usually treated as the familyDirachmaceae, inGeraniales, but a position inMalvales has also been suggested. Analyses of molecular data, from bothrbcL andtrnL-F, indicate thatBarbeya andDirachma are closely related inter se as well as toRhamnaceae andElaeagnaceae. In an analysis based on morphologyBarbeya groups withElaeagnaceae, andDirachma withRhamnaceae andUlmaceae. In a combined molecular and morphological analysisBarbeya is the sister group ofElaeagnaceae andDirachma is the sister group of the wholeBarbeya-Elaeagnaceae-Rhamnaceae clade. However, the support for these arrangements is weak and, rather than mergingBarbeyaceae withDirachmaceae as suggested by the molecular analysis or withElaeagnaceae as suggested by the morphological and combined analyses, it seems best to retain bothBarbeyaceae andDirachmaceae in their present circumscriptions, but in both cases in completely new positions in the angiosperm system. The results are compatible with a new circumscription ofRhamnales comprisingRhamnaceae, Elaeagnaceae, Dirachmaceae andBarbeyaceae.