Phylogenetic position of Madagascan species of Acacia s.l. and new combinations in Senegalia and Vachellia (Fabaceae, Mimosoideae, Acacieae)

Abstract

The recent worldwide effort to transfer all non-Australian taxa of Acacia s.l. mostly to the genera Senegalia and Vachellia follows the acceptance of the proposed re-typification of the genus with an Australian species. The Madagascan species have, as yet, not been included in phylogenetic studies of Acacia s.l. and their position in the new generic classification of Acacia s.l. is therefore still unclear. In this study, plastid DNA sequence data were generated for seven Madagascan species, included in existing matrices for Acacia s.l. and analysed to assess the placement of these species. The results indicate that the Madagascan species are placed either in Senegalia or Vachellia and conform to the morphological characters used to distinguish these genera, despite some taxa having unusual red flowers. New combinations are formalized for Senegalia baronii, S.hildebrandtii, S.kraussiana ssp. madagascariensis, S.menabeensis, S.meridionalis, S.pervillei, S.pervillei ssp. pubescens, S.polhillii, S.sakalava, S.sakalava ssp. hispida, Vachellia bellula, V.myrmecophila and V.vigueri. Nomenclatural errors are also corrected for three African taxa and, as such, new combinations are provided for Senegalia fleckii, S.hamulosa and Vachellia theronii.