Wikipedia
Hymenasplenium
Hymenasplenium is one of three genera of ferns in the Aspleniaceae (spleenwort family), in the eupolypods II clade of the order Polypodiales. The others are Hemidictyum and Asplenium. Hymenasplenium was segregated because it is a natural grouping with differing rhizome morphology – dorsiventral v. radial for the rest of Asplenium, differing chromosome count – x=39 v. x=36 for the rest of Asplenium, and a clear monophyletic grouping based on genetic analysis. It was confirmed as a sister group to Asplenium in a 2015 molecular study of the genera.