New insights into the phylogeny of Pleopeltis and related Neotropical genera (Polypodiaceae, Polypodiopsida)

The fern family Polypodiaceae plays an important role in Neotropical epiphyte diversity. Most of its American representatives are assembled in a monophyletic clade that, apart from the grammitids, nearly exclusively comprises species restricted to the New World. The phylogenetic relationships of these ferns are still insufficiently understood and many taxonomic problems, such as natural circumscriptions of the genera Polypodium and Pleopeltis, were unresolved. Here we address one of the two main lineages within New World Polypodiaceae including Pecluma, Phlebodium, Pleopeltis, and Polypodium. Our study is based on DNA sequence data from four plastid regions that were generated for 72 species representing all putative major taxonomic groups within this lineage. The analyses reveal three major clades: (1) Polypodium plus Pleurosoriopsis; (2) Pecluma plus Phlebodium, and some species of Polypodium; and (3) Pleopeltis and related genera. The last clade contains species of Pleopeltis and Polypodium as well as Microphlebodium, Neurodium, Dicranoglossum, and Pseudocolysis. All species included in the clade display conspicuous persistent peltate laminar scales that are not found in other species of this lineage. Our results suggest a reconsideration of the generic concept of Pleopeltis with peltate laminar scales being the genus' key character.