Phylogenetic placement of Ivodea and biogeographic affinities of Malagasy Rutaceae

Abstract

Abstract The genus Ivodea is endemic to Madagascar and the Comoros and consists of 30 species. This study is the first to include the genus in a molecular phylogenetic analysis. We sequenced the plastid trnL–trnF and the nuclear ITS regions for three Ivodea species and revealed that the genus is monophyletic and most closely related to the African and Malagasy Vepris, refuting earlier suggestions of a close relationship between Ivodea and the Asian, Malesian, Australasian and Pacific genera Euodia and Melicope. Ivodea and Vepris provide another example of closely related pairs of Rutaceous groups that have drupaceous and capsular/follicular fruits, respectively, thus further confirming that fruit types are not suited to delimit subfamilies in Rutaceae, as has often been done in the past. Ivodea was the last of the seven Malagasy genera to be included in the Rutaceae phylogeny, making it possible to conduct an assessment of biogeographic affinities of the genera that occur on the island. Our assessments based on sister-group relationships suggest that the eight lineages (representing seven genera) of Malagasy Rutaceae either have African or have Asian affinities. Two lineages have an African origin, and one lineage has an Asian origin. Taxon sampling is insufficient to interpret the directionality of dispersal events in the remaining lineages.