Abstract:The chloroplast trnL intron and trnL-trnF intergenic spacer (IGS) sequences of one species in Dicksoniaceae (Cibotium barometz) and 11 species in Cyatheaceae were determined by sequencing cloned PCR products or amplified fragments directly (for Alsophila spinulosa and Cyathea tsangii, 9 and 2 individuals were sequenced, respectively). Sizes of the sequences of the 12 species ranged between 1004 bp to 1082 bp. The average contents of (A+T)% and (G+C)% were 60.9% and 39.1%, respectively. The base differences (transition/transversion) and Kimura's genetic distances were also computed between different species and intraspecific individuals. After sequence alignment, maximum parsimony, maximum likelihood and neighbor-joining methods were used to conduct phylogenetic analyses. The results indicated that Xia's classification of Chinese Cyatheaceae was supported, the dade consisting of Sphaeropteris brunoniana, Sphaeropteris hainanensis and Cyathea contaminans firstly diverged from the rest members of the family, and the latter was further separated into two subclades corresponding to the subgenus Alsophila and subgenus Gymnosphaera. Three monophyletic terminal clades, within each the pairwise genetic distances were less than 0.008, were formed separately by Cyathea gigantean-C. pseudogigantea-C. tinganensis-C. pectinata, C. contaminans-Sphaeropteris brunoniana-S. hainanensis, and Cyathea tsangii-Alsophia spinulosa, suggesting that these species could be combined as three separate species: Cyathea gigantean, Sepaeropteris brunoniana and Alsophila spinulosa. The genus Sphaeropteris was placed in the basal position of Cyatheaceae, whereas the genus Alsophila placed as the derived sister group, which supported Tryon's hypothesis accounting for the evolutionary relationships within Cyatheaceae and the derivation of their indusium.
