Phylogenetic Position of the Enigmatic Fern Genus Weatherbya (Polypodiaceae) Revisited: Evidence from Chloroplast and Nuclear Gene Regions and Morphological Data

Premise of research.Weatherbya is a small genus of subfamily Microsoroideae (Polypodiaceae) with controversial phylogenetic placements. In this study we aim to test the phylogenetic hypotheses about Weatherbya utilizing chloroplast and nuclear genes from an extensive generic sampling of Microsoroideae.Methodology.Phylogenetic analyses of DNA sequences from four chloroplast DNA markers (rbcL, rbcL-atpB, trnL-F, and rps4+rps4-trnS) of 13 genera (Phymatosorus was treated as a separate genus) in Microsoroideae and a nuclear gene (LEAFY) of Weatherbya and four related genera were conducted. Morphological evidences including characters of leaf epidermis and rhizome scales were described in Weatherbya and the mostly related genera.Pivotal results.Results of the phylogenetic analyses of both chloroplast (except rps4+rps4-trnS) and nuclear genes strongly support Weatherbya embedded in Lepisorus. The chloroplast rps4 gene includes internal stop codons in many taxa of Microsoroideae, and this gene has been reported under selection.Conclusions.Phylogenetic analyses strongly support the inclusion of Weatherbya in Lepisorus rather than Lemmaphyllum, and their close relationship is supported by similar morphology of rhizome scales and leaf epidermis.