The classification of the fern family Gleicheniaceae, with the description of a new genus, segregated from Sticherus

Abstract

Gleicheniaceae is an early diverging lineage of leptosporangiate ferns. Although the family can be readily recognized by the pseudodichotomous branching pattern of its fronds, generic circumscription has long been debated. Phylogenetic analyses based on genomic data supported the monophyly of six genera (Dicranopteris, Diplopterygium, Gleichenella, Gleichenia, Rouxopteris, and Stromatopteris) but indicate the paraphyly of Sticherus. To accommodate this latter result, we describe a new genus, Sticheropsis, gen. nov., segregated from Sticherus. We provide a new taxonomic treatment of Gleicheniaceae, including an identification key to all eight genera, descriptions of the genera with comments and notes concerning geographic distributions and phylogenetic affinities, as well as an overview of the morphology of the family with a revised and unified terminology for the fronds. We recognize 149 species plus two hybrids for the family, distributed into eight genera, and propose six new combinations.