Toward a monophyletic Cheilanthes: The resurrection and recircumscription of Myriopteris (Pteridaceae)

The fern genus Cheilanthes (Pteridaceae) has perplexed taxonomists for more than two centuries. Complex patterns of evolution involving rampant morphological convergence, polyploidy, hybridization, and apomixis have made the taxonomy of this group especially difficult. Fortunately, recent phylogenetic analyses have helped to clarify relationships among cheilanthoid taxa. Based on these findings, we here formalize an updated taxonomy for one monophyletic clade comprising 47 primarily North and Central American taxa usually included in Cheilanthes. Because the type species of Cheilanthes (Cheilanthes micropteris) is only distantly related to this clade, we resurrect the genus Myriopteris to accommodate these taxa, and present a revised circumscription for the group, including 36 new combinations.