Phylogeny and taxonomy of Leucotrichum (Polypodiaceae): A new genus of grammitid ferns from the Neotropics

A new genus of grammitid ferns, Leucotrichum, is described. Segregated from Lellingeria on the basis of molecular analyses and morphological characters, it comprises five species distributed in the Antilles, Central America, and Southeastern Brazil. We present a phylogeny based on two cpDNA genes, atpB and rbcL, showing the relationships between Leucotrichum and other genera of grammitid ferns. Both Bayesian and Maximum Parsimony analyses support the monophyly of Leucotrichum, with bootstrap value of 100% and posterior probability value of 1.0, and its sister-group relationship to the Terpsichore lanigera group. Leucotrichum is characterized by seven morphological characters: arching fronds, clathrate rhizome scales, blackish rhizome scale cell walls, laterally marginate petioles, laminar apices subconform to the lateral pinnae, pinna costae without blackish sclerenchyma, and hairs bearing acicular branch cells. We also provide a key, descriptions, complete synonymy, discussions, specimens examined, and illustrations for all the species.