Taxonomic Revision Of Onychium Kaulf. In Pan-Himalaya

Onychium Kaulf. is one of the genera in Pteridaceae with ca.10 species. It’s mainly distributed in tropical and subtropical Asia. As variations of the plant are common and complex, convergent evolution occurs in morphological characters, the study is not enough and comprehensive, there have been many obstacles in the work of classification and identification, and extensive controversies among the different scholars. Besides, the taxonomic treatment of some species in Onychium is not satisfied and should be revised. Based on a large of herbarium work, literature research, as well as the evidence of micromorphology, molecular phylogeny and so on, the morphological features of Onychium in Pan-Himalaya and neighboring regions were analyzed, and the taxonomic revisions were done, in order to make a contribution to the editing of Flora of Pan-Himalaya.Throughout studying over 3000 sheets of species from more than 10 herbaria all over the world, and researching the previous references comprehensively, as well as doing thorough field work, we can get results that the morphology of rhizomes, ways of leaf branching, shapes of indusial on fertile pinnules and the morphological characteristics of apical serrations on ultimate pinnules, as well as the microstructures of scales are the most important characters for species classifications.In this study, five chloroplast DNA sequences (rbcL/atpA/matK/trnL-trnF/trnG-trnR) were employed, and 9 taxa were used to reconstruct the phylogeny of Onychium. The results indicates that Onychium is a natural monophyletic group. All species of Onychium were clearly divided into two main groups:Onychium japonicum (Thunberg) Kunze, O. tibeticum Ching & S. K. Wu, O. moupinense Ching, O. moupinense var. ipii (Ching) K. H. Shing, O. lucidum (Don) Spreng, O. contiguum Christ and O. plumosum Ching were clustered in a group, while O. siliculosum (Desvaux) C. Christensen and O. tenuifrons Ching were clustered in another group. This can provide molecular evidences for the taxonomy of Onychium.Based on all the studies above, the taxonomic treatment was given. Eight species were recognized in Pan-Himalayas. The revised descriptions, maps of distributions and the key to every species were provided.