A global phylogeny of the fern genus Tectaria (Tectariaceae: Polypodiales) based on plastid and nuclear markers identifies major evolutionary lineages and suggests repeated evolution of free venation from anastomosing venation.

ABSTRACT

Tectaria (Tectariaceae) is one of the most confusing fern genera in terms of its circumscription and phylogeny. Since its original description, a number of genera had been moved into or related with this genus, while others had been segregated from it. Tectaria is also among the largest fern genera, comprising 150-210 mostly tropical species. Previous molecular studies have been far from comprehensive (sampling no more than 76 accessions from 52 species), limited in geographic scope (mainly restricted to Asia), and based exclusively on plastid markers. In the present study, DNA sequences of eight plastid and one nuclear marker of 360 accessions representing ca. 130 species of Tectaria, ca. 36 species of six non-Tectaria genera in Tectariaceae, 12 species of Davalliaceae, Oleandraceae, and Polypodiaceae, and 13 species of Lomariopsidaceae were used to infer a phylogeny with maximum likelihood, Bayesian inference, and maximum parsimony approaches. Our major results include (1) the most recently proposed circumscription of Tectaria is strongly supported as monophyletic; (2) the genera Lenda, Microbrochis, Phlebiogonium, and Sagenia, sampled here for the first time, are resolved as part of Tectaria; (3) four superclades representing early splits in Tectaria are identified, with the Old World species being sister to the New World species; (4) 12 well-supported major clades in Tectaria are revealed, differing from one another in molecular, morphological, and geographical features; (5) evolution of 13 morphological characters is inferred in a phylogenetic context and morphological synapomorphies of various clades are identified; and in particular (6) free venation in Tectaria is inferred to be repeatedly derived from anastomosing venation, an evolutionary phenomenon not documented previously in vascular plants in a phylogenetic context based on both plastid and nuclear evidence.