Phylogenetic relationships of the enigmatic fern families Hymenophyllopsidaceae and Lophosoriaceae: Evidence from rbcL nucleotide sequences

Abstract

Nucleotide sequences from rbcL were used to infer relationships of Lophosoriaceae and Hymenophyllopsidaceae. The phylogenetic positions of these two monotypic fern families have been debated, and neither group had been included in recent molecular systematic studies of ferns. Maximum parsimony analysis of our data supported a sister relationship between Lophosoria and Dicksonia, and also between Hymenophyllopsis and Cyathea. Thus, both newly-examined families appear to be part of a previously characterized and well-supported clade of tree ferns. The inferred relationships of Lophosoria are consistent with most (but not all) recent treatments. However, Hymenophyllopsis includes only small delicate plants superficially similar to filmy ferns (Hymenophyllaceae), very different from the large arborescent taxa. Nevertheless, some synapomorphic characteristics are shared with the tree fern clade. Further studies on gametophytes of Hymenophyllopsis are needed to test these hypotheses of relationship.