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Malte Ebinghaus, Michael J. Wingfield, Dominik Begerow, Wolfgang Maier

• The genus \(\it Ravenelia\) represents the third largest genus of rust fungi and parasitizes a great number of leguminous shrubs and trees, mainly in the subtropics and tropics. Molecular phylogenetic analyses of this genus using nc 28S rDNA and \(\it CO3\) sequences are presented with a special focus on South African representatives of \(\it Ravenelia\). Many of the specimens had been collected by us in recent years, mainly from acacia species of the genera \(\it Vachellia\) and \(\it Senegalia\). Morphological characters were extensively studied using light microscopy and scanning electron microscopy. The analyses resolved several well-supported phylogenetic groups. By linking these groups to their morphology and life cycle characteristics, it was possible to interpret the outcomes in terms of their evolutionary ecology and biogeography. Several characters previously used to define subgeneric groups within \(\it Ravenelia\) were found to be misleading because of assumed convergent evolution. However, host associations, the ability to induce aecial galls as well as the development of two-layered probasidial cells emerged as useful criteria for inferring monophyletic groups. Six novel \(\it Ravenelia\) species were discovered and described. Furthermore, five species represent new reports for South Africa, species descriptions were emended for two taxa, and a new host report emerged for \(\textit {R. inornata}\).