Athyrioid ferns（Athyrioideae, Dryopteridaceae）consist of about 700 species with a distribution range from tropical to temperate zone in the world. In Taiwan, the subfamily includes 50 species commonly found from lowland to around 3000 meters in elevation. Phylogenetic relationships and the generic circumscription of athyrioid genera are confused and controversial. In this study, trnL-trnF spacer, which is a nucleotide sequence between genes in the chloroplast, was used to analyze and infer the phylogenetic relationships and evolutionary status of 35 species.
Phylogenetic trees produced by neighbor-joining and maximum-parsimony methods are similar in topology. Athyrium and Cornopteris form a clade, and this indicates Cornopteris is more closely related to Athyrium than to Diplazium. Anisogonium nests within Diplazium clade, and it implies these two genera congeneric. Anisocampium is distinct from Athyrium sensu stricto and forms a clade with Athyrium nipponicum. Deparia clade includes Athyriopsis, Lunathyrium, Dryoathyrium, Dictyodroma, Diplazium subsinuatum and Matteuccia. These four clades may be seen as the core part of athyrioid ferns. Woodsia and Thelypteridaceae cluster next to these four clades. Cystopteris and Gymnocarpium occupy a position between Thelypteridaceae and Dryopteridaceae. Rhachidosorus is neither closely related to Athyrium nor Diplazium. Hypodematium is distantly related to athyrioid ferns and forms a clade with Dryopteridaceae. Therefore, Hypodematium may be isolated from athyrioid ferns.
Based on the evidences mentioned above, athyrioid ferns are suggested to be closely related to Thelypteriaceae, and are probably members of Woodsiaceae（including Thelypteridaceae）instead of Dryopteridaceae. In addition, Cystopteris and Gymnocarpium are the most basal lineage of Woodsiaceae sensu lato. The core group of athyrioid ferns probably better treated as a monophyletic tribe or subfamily of Woodsiaceae at current stage.