Diversity and taxonomy of the fern genus Vandenboschia Copel. (Hymenophyllaceae, Polypodiidae) in the Afro-Malagasy region and description of a new species

Vandenboschia radicans (supposedly Neotropical and African), V. speciosa (supposedly European and Macaronesian) and V. gigantea (supposedly from western Indian Ocean) are morphologically close species and often confused in collections and in floras. Moreover, the status of African populations is still strongly debated. We undertook to combine morphological, morphometrics and molecular phylogenetic analyses, on these three species, by also including the Neotropical V. collariata, morphologically close to V. radicans, to try to discriminate putative geographical lineages and discuss their taxonomic status. Our results show that V. collariata is distinct from the other species, and that V. radicans, V. speciosa, V. gigantea and the African specimens remain morphologically and morphometrically indistinguishable. Nevertheless, the Neotropical specimens of V. radicans, V. speciosa and V. gigantea are each genetically strongly distinct and are thus clearly supported as distinct species. African specimens are all grouped into a distinct clade sister to V. gigantea and are distinguished by the presence of a well-developed wing on the stipe, lacking in V. gigantea. Taking into account this stipe feature as well as genetic differences, we describe here Vandenboschia confusa as a new species corresponding to the African populations. The origin of this species in the region is discussed, in addition to the complex taxonomy of European-Macaronesian V. speciosa.