Arachniodes × tohtomiensis hyb. nov. (Dryopteridaceae) from Japan

This study aims to characterize a hybrid of Arachniodes (Dryopteridaceae), A. × tohtomiensis , for which molecular evidence of its origin and detailed morphological descriptions are lacking. The genome composition of A. × tohtomiensis , clarified based on plastid DNA and MIG-seq analyses, indicates that it is a diploid hybrid of A. exilis and an undetected species. This origin was also supported by phylogenetic, STRUCTURE, principal component, and neighbor-net analyses. Based on these evidences, it is formally described as A. × tohtomiensis Shimura & Hori, hyb. nov . It is morphologically characterized by its yellowish-green laminae and erose-to-ciliate indusia.