The Preliminary Study Of Molecular Phylogeny On Ptychomitrium

Based on collections of plant samples both from the herbaria and field investigation, the molecular experiments of the representative species of the moss genus Ptychomitrium in the world were carried out by DNA sequences technology. Combining molecular data with morphological characters, the phylogeny and pattern of geographic distributiaon of the genus Ptychomitrium were analyzed. The valuable results are as follows:1) Among the 38 species that have been researched, those species with dentate leaf edge are obviously different from those with entire leaf edge. The relationships between those species with entire leaf edge are complicated. However, relationships between species with dentate leaf edge are simple and they are more evolved. In this genus, entire leaf edge is a kind of plesiomorphic.2) Guo (1999) considered that the genus Ptychomitrium were divided into two progenies. The progeny on Laurasia evolved into the present species with dentate leaf edge which are on north hemisphere now, the progeny on Gondwanaland evolved into the species with entire leaf edge which are on south hemispere now. In our study, the evolution tendence is same with his opinion obviously. Analyzing from the biogeographic point, species from Africa, South America and Australia are in close relation, and most of them are with entire leaf edge. Some evolved species with dentate leaf edge are distributed in East Asia.3) About the taxonomic position of Ptychomitriopsis aloinoides, there are two different opinions. The results of our study tend to leave it in the genus Ptychomitrium.4) Ptychomtirum sinense is a dispersedspecies. Their morphological characters changs obviously. In our phylogenetic trees, their positions are dispersed. We suggest to taking further study on it based on both morphological and molecular methods.5) Ptychomitrium gardneri and P. polyphylloides are synonyms and should be merged into one species based on Cao and Guo's opinion. The result provides molecular data to their thesis. Ptychomitrium depressum and P. sellowianum are synonyms too, in the phylogenetic trees, they are close. But we are not sure if they should be merged. Further study should be made on them.6) The morphologies of Ptychomitrium crispatum and P. subcrispatum are similar. Their positions in phylogenetic tree are close. Further molecular study should be made in the future to make sure their taxonomic position.7) There are different systematic opinions about two species, Ptychomitrium australe and P. acutifoliu. 16 sequences are received from four samples of them. After analysis, their positions in the phylogenetic trees are obviously different, so they should be two independent species and not the synonyms of each other.8) Both Ptychomitrium lepidomitrium and P. formosicum have undate thicken cells in under part of the leaves. This character is evolved. In phylogenetic trees, they are close and that meant they had close evolution position.