Molecular Phylogeny Of The Asian Cheilanthoid Ferns

Most species of cheilanthoid ferns have undergone convergent evolution in morphology, which have broad influences on the reconstruction of phylogentic relationships in this group. The systematic relationship of this group has always been a difficult problem confused with scholars in the domestic and foreign country. In this study, we chose 50 species representing cheilanthoid ferns and its related group. Based on eight chloroplast genome DNA fragments (matK, rbcL, atpA, trnG, rps4, rps4-trnS, trnG-trnR, trnL-F), we reconstructed molecular phylogeny of the groups in order to reasonably solve the definition problem between genera using three methods:maximum parsimony (MP), maximum likelihood (ML) and Bayesian analysis.The results show that:(1) Aleuritopteris pseudofarinosa in ser. Farinosae and A. shensiensis、 A. subargentea、A. argentea、A. duclouxii and A. duclouxii var. sulphurea of ser. Argenteae formed a strongly supported clade (Bootstrap value=100%), which indicated that these species have close relationship; A. squamosa、A. rosulata、A. likiangensis and A. veitchii in ser. Argenteae and A. chrysophylla、A. humatifolia、A. rufa、A. albomarginata、A. grisea、A. formosana and A. ebnipes of ser. Farinosae formed a strongly supported clade, indicating that they have close relationship. But these branches mixed together with other genera, so we still put them in the Asian Cheilanthes group; Aleuritopteris humatifolia and A. chrysophylla of Aleuritopteris formed a strongly supported clade (bootsrap value= 100%) in systematic tree, which showing the two species have close relationship. We support the taxonomic treatment of reducing A. humatifolia to synonym of A. chrysophylla based on our phylogenetic analysis combining the evidences from their morphological characters of blades, spores, indusia, and rhizome scales. (2) Cheilosoria tenuifolia of Cheilosoria and Notholaena hirsuta formed a strongly supported clade (bootsrap value= 100%) in systematic tree, staying away from Asian cheilanthes group, which showing the two species have close relationship. Combining withvarious evidence, we think C. tenuifolia and Notholaena hirsuta should be divided out from the Asian cheilanthes group. (3) Pellaea connectens from Chinese Pellaea and five members from American Argyrochosma formed a strongly supported clade (bootsrap value= 100%). P. connectens have typical odd pinnate, which is very different with other species of Chinese Pellaea. Thus, we think P. connectens should be classified in Argyrochosma. P. calomelanos was far away from the rest members of Chinese Pellaea and have a close relationship with Doryopteris, so we temporarily gave P. calomelanos a separate group treatment.