Dryopteris xmakabensis (Dryopteridaceae), a New Hybrid between Dryopteris caudipinna and D. tokyoensis

A new hybrid, Dryopteris xmakabensis (Dryopteridaceae) is described from Ibaraki Prefecture, Japan. Morphological observations, ploidy analysis, as well as nuclear and plastid DNA analyses, indicate that this diploid sterile hybrid likely originated from a cross between D. caudipinna and D. tokyoensis. Its occurrence is likely infrequent because the habitats of the parents are usually non -overlapping in Japan.