Phylogeny, infrageneric classification and species delimitation in the Malagasy Impatiens (Balsaminaceae)

Abstract. The species-rich genus Impatiens (Balsaminaceae) is represented in Madagascar by no less than 260 species. We conducted molecular phylogenetic analyses of the Malagasy Impatiens based on nuclear and plastid data and 52 accessions (representing 33 species) to: 1) reassess the monophyly of the Malagasy Impatiens; 2) assess the monophyly of the sections Preimpatiens (Humblotianae and Vulgare groups) with spurs and Trimorphopetalum without spurs as delimited by Perrier de la Bâthie, as well as that of the subgenera Impatiens and Trimorphopetalum as defined by Fischer and Rahelivololona; 3) infer the current status of some morphologically variable species; and 4) test whether the species of Impatiens from the Marojejy National Park form a monophyletic group. The Malagasy Impatiens are further confirmed to be paraphyletic with respect of the Comorian I.auricoma. The present sectional and subgeneric classifications of the Malagasy Impatiens are partly supported, with strong support for the monophyly of the sect. or subgen. Trimorphopetalum. Section Preimpatiens was not supported as monophyletic and neither the Humblotianae group nor the Vulgare group is monophyletic. Impatienselatostemmoides, I. “hammarbyoides”, I.inaperta, I.lyallii and I.manaharensis are either para- or polyphyletic and may represent morpho-species. The Impatiens species from the Marojejy National Park do not form a monophyletic group and therefore are suggested to be derived from numerous independent colonisation events from all over Madagascar followed by subsequent diversifications.