Sang Hee Park1P, Hyoung Tae Kim2, Jung Sung Kim1

1Department of Forest Science, Chungbuk National University, Cheongju

2Department of Crop Science, Kyungpook National University, Sangju

Species delimitation in ferns is challenging due to limited diagnostic morphological characters and frequent hybridization and polyploidization, which generate reticulate evolutionary patterns among closely related taxa. These problems are particularly pronounced in the family Hymenophyllaceae and Aspleniaceae, for which taxonomic treatments in Korea have largely relied on morphological classification alone. To reassess species identities and phylogenetic relationships in these families, this study applied an integrative approach combining cytogenetic data with molecular phylogenetic analyses. For the Hymenophyllaceae, morphological investigations and cytogenetic analyses, together with molecular phylogenetic analyses using one chloroplast region (rbcL) and one nuclear region (gapCp), revealed an unreported triploid Hymenophyllum barbatum, a tetraploid H. wrightii, one new hybrid, one unrecorded hybrid, and one cryptic species. Based on these findings, the Korean Hymenophyllaceae are now recognized as six taxa of Hymenophyllum, four of Crepidomanes, and five of Vandenboschia. For the Aspleniaceae, cytogenetic analyses were integrated with molecular phylogenetic analyses using three chloroplast regions (rbcL, trnL–F, trnH–psbA) and one nuclear region (pgiC). This approach identified a new triploid Asplenium ×castaneoviride, an octoploid A. prolongatum, one new species, one putative new species, and three sterile unrecorded hybrids. As a result, the Korean Aspleniaceae are now recognized as comprising 28 taxa of Asplenium and one of Hymenasplenium. Overall, this study demonstrates that Korean fern diversity has been underestimated and highlights the importance of integrative cytogenetic and molecular approaches for accurate species delimitation. This framework provides a robust basis for detecting additional new or cryptic fern taxa and for improving our understanding of fern evolution in East Asia.