A Phylogenetic Study And Geographical Distribution Of Genus Racomitrium Sensu Lato In The World

Based on the specimens of Racomitrium and original literatures, classificationand morphology description of57Racomitrium species were stated and thegeographical distribution pattern of85Racomitrium species in the world was studied.58specimens, naming16Racomitrium species collected from Asia, Europe, NorthAmerica and South America, were used in the molecular systematic. Three choloplastgenes trnL, trnG, psbT and nuclear gene ITS2were included. After sequences werereceived, Phyde, PAUP, Mrbayes et al. were used for building trees and systematicanalysis. According to the morphological characteristics of Racomitrium,geographical distribution pattern and molecular tata, several conclusions are asfollows:1.85species of genus Racomitrium were comfirmed in the world, and establishedthe key to57species of Racomitrium with morphological descriptions.2. The geographic distribution of85species of Racomitrium was counted in the20areas of the world. It was predicted that the species of which leaf cells weresmooth was the ancestors of Racomitrium. And it evolved into two branches ofleaf cells smooth and leaf cells with papillose.3. According to the topology structure of molecular phylogenetic tree and thesupporting values, the following results were obtained:a. The phylogenetic trees show that58specimens of Racomitrium involvedwere monophyletic, sister of Grimmia and Jaffueliobryum. And the result ofthe study doesn’t support the view that genus Racomitrium was advanced tothe position of subfamily, which should be treatd as Racomitrium sensu lato. b. In the phylogenetic trees,16Racomitrium species was divided into9sections:Sect. Racomitrium, Sect. Marginata, Sect. Sudetiaca, Sect. Subsecunda, Sect.Laevifolia, Sect. Stenotrichum, Sect. Fasciculare, Sect. Canescentia and Sect.Elongta. To some extent, this supports the point that Racomitrium in theworld may be divided into15sections: Sect. Canescentia, Sect. Elongata,Sect. Racomitrium, Sect. Fascicularia, Sect. Chrysea, Sect. Pilifera, Sect.Stenotrchum, Sect. Marginata, Sect. Laevifolia, Sect. Lawtonia, Sect.Sudetica, Sect. Subsecunda, Sect. Ellipticodryptodon, Sect. Emersa, Sect.Ptychophylla. However, the limit of the specimens leads to the further studyin the future.c. It is suggested that Subgen. Bucklandialla and Subgen. Codriophorus shouldbe redefined, which were part of four subgenera (Subgen. Racomitrium,Subgen. Bucklandialla, Subgen. Codriophorus and Subgen. Niphotrichum) ofRacomitrium promoted by Ochyra. Because the branches were mixed basedon divisions.d. Sometimes Sect. Laevifolia was with pseudopapilose in the leaf cells. Thissection and the Racomitrium species with papillose were in the same branch.Therefore, it is suggested that Sect. Laevifolia should be part of Racomitriumwith papillose.e. Racomitrium aciculare and Racomitrium aduncoides were usually in the samebranch. It means that none single section or subgenus branch was formed byR. aciculare. So the result of the study doesn’t support that R. aciculare beadvanced to subgenus, which still should be regarded as species.