Taxonomic Revision And Potential Geographical Distribution Of Didymodon Vinealis In China

The Division Bryophyta group includes Division Bryophyta,Music,Anthocerotae,Bryophytes,as the lower group of higher plants,are second only to angiosperms in number of species.Didymodon vinealis(Brid.)R.H.Zander,belonging to genus Didymodon Hedw.,Pottiaceae,Musci.Plants in dense tufts,stem erect,simple,rarely branched,in transverse section rounded,leaves appressed and incurved when dry,spreading when moist,triangular to lanceolate.Due to the strong morphological plasticity of D.vinealis,some key features are not easy to distinguish,there are some difficulties and controversies in species classification and identification,which leads to some limitations in the physiological and ecological studies of D.vinealis.In this study,a combination of morphological anatomy,molecular systematics and construct model,we observed and compared the morphological and structural characteristics of D.vinealis by referring to a large number of literatures and borrowing from bryophyte herbarium;the suitable areas of D.vinealis was selected for specimen collection;phylogenetic tree was constructed based on nuclear gene(ITS)and chloroplast gene(rps4,trn M-trn V),to clarify the morphological classification characteristics and systematical classification status of D.vinealis,in addition,the distribution pattern of D.vinealis in China was simulated by using the point information recorded and the primary data obtained from our systematic survey,furthermore,its geographical distribution in China and the relationship between its distribution and different types of climate and topography were determined,the main conclusions of this study are as follows:1.Morphological studies of specimen inspection and sample collection showed that there were differences in the number of papillae,and in the presence of translucent cells below the apex on the ventral surface between D.vinealis in China and D.vinealis in Europe and America.The main difference is that there are no long transparent cells in the upper ventral side of the middle rib near the leaf tip and 1-3 of the2.Molecular systematics studies showed that D.vinealis in China and D.vinealis in Europe and America was far from each other,it is consistent with the results of morphological studies,therefore,it was classified as Didymodon sinensis J.Kou & C.Feng.3.Geographical distribution studies show that the D.sinensis mainly distributed in Inner Mongolia,Tibet and the middle and high altitude areas of Southwest China,in addition,it also has a small distribution in semi-humid areas of China,however,the distribution centers are mainly semi-arid areas,in terms of geographical distribution pattern,it is different from D.vinealis which is the world's most widely distributed species.4.Annual precipitation,Precipitation of warmest quarter and Elevation are mainly factors of the distribution of D.sinensis,it is the reason for the difference in the geographical distribution pattern between D.sinensis and D.vinensis.5.In conclusion,based on morphology and molecular phylogenetic studies,the ph ylogeny of D.vinealis in China is far from the D.vinealis in Europe and America,a nd they are not identical species,the spatial distribution is different from the recorded in the existing Moss annals,therefore,it was classified as Didymodon sinensis.