The significance of Rouxopteris (Gleicheniaceae, Polypodiopsida): a new genus endemic to the Madagascan region
Résumé
Gleichenia boryi is a poorly known species of Gleicheniaceae endemic to Madagascar and La Réunion Island. Although Kunze pointed out in his description that this fern was distinct from other Gleicheniaceae in its leaf morphology, the generic relationships of this fern have not been investigated until now. Taking advantage of DNA sequences obtained from a sample of this species obtained in La Réunion Island and a sample of the type species Gl. polypodioides, we tested the hypothesis that the morphological distinction reflects the phylogenetic isolation of Gl. boryi. By reconstructing the phylogenetic relationships and divergence time estimates, we were able to show that this fern is not closely related to Gleichenia s.s. and represents a distinct lineage segregated from other Gleicheniaceae since the Cretaceous. Thus, a new generic name Rouxopteris (gen. nov.) and a new combination R. boryi (comb. nov.) are introduced to improve the generic classification of this family. We also discussed the evolutionary history of the Gleicheniaceae in the context of the Cretaceous terrestrial revolution.