Molecular phylogeny of the fern family Blechnaceae (Polypodiales) with a revised genus-level treatment

Abstract

Blechnaceae, a leptosporangiate fern family nested within eupolypods II, comprises 200–250 species, typically divided among seven to nine genera. Despite recent molecular studies of the family, it still lacks a modern taxonomic update based on broad sampling from the two centres of diversity—the Neotropics and Australasia/Oceania. To test generic circumscriptions, we have assembled the broadest dataset thus far, from three plastid regions (rbcL, rps4-trnS, trnL-trnF) and with taxonomic sampling focused on both major diversity centres. Our sampling includes 156 taxa and 178 newly generated sequences. We recognize three subfamilies, each corresponding to a highly supported clade across all analyses (maximum parsimony, Bayesian inference and maximum likelihood). The genera Salpichlaena, Stenochlaena and Telmatoblechnum are monophyletic, while Blechnum is polyphyletic, because Brainea, Doodia and Sadleria all nest within it. We outline and explain a plan to resolve the polyphyly of Blechnum by recognizing additional, monophyletic, segregate genera.