A New Hexaploid Species of

A new endemic species of Isoetes from Fujian, China, which was previously identified as I. orientalis, is described and illustrated. In this study, we observed its leaf cross-cut characteristics under a microscope and spore morphology characteristics under a scanning electron microscope, counted its chromosome number, and compared population genetic differences between this hexaploid and I. orientalis based on single nucleotide polymorphisms (SNPs) extracted from whole-genome resequencing data. We found that this hexaploid differs from I. orientalis in both leaf morphology and spore ornamentation, and that the two also exhibit significant differences in population genetics. Based on this comprehensive evidence, we identified the hexaploid as a new species and named it I. fokiensis. Here, we formally describe this hexaploid species and provide an identification key to the Isoetes species reported from China.