Application Of DNA-barcoding Technique In The Taxonomy Of Lichen Genus Physconia From Hengduan Mountians

The lichen genus Physconia Poelt belongs to the family Physciaceae,mainly characterized by: thallus foliose,upper surface often covered with varying degrees of white pruina,the upper cortex is mostly prosoplectenchymatous,lower surface has black cortex,with or without squarrosely branched rhizines;apothecia laminal and Lecanora-type,the discs are also covered with white pruinose,the margin often developing lobules or soredia;ascospores 1-septate,brown.A total of 18 species of Physconia were reported in China,including 6 species of Hengduan mountain.No molecular data was provided for all species.Early taxonomic studies were mainly based on morphological characteristics,which were largely subjective.The species determined were close to species in European and north American morphology.It may even mix with species from other families and genera,leading to difficulties in species identification and confusion in classification.At present,there is a lack of systematic study on the whole taxa in China,and the unclear classification boundary makes the systematic study and geographical distribution of the species in this genus are difficult to be clarified.Through the application of DNA-barcoding technology in the classification of the genus Physconia.DNA from samples collected in the past five years was extracted.The selection of ITS and other molecular sequences as target fragments can be used to classify and identify the species of Physconia.To effectively supplement the molecular sequences of the species of Physconia and its related genus in China,and to to provide some scientific basis for the establishment of the natural classification system of Physconia.Phylogenetic tree was constructed,the phylogenetic relationship between genera and species was discussed,and the species of this genus were objectively classified and defined in Hengduan mountain area.The results showed that the phylogenetic tree constructed with molecular sequences could be used for the identification of Physconia species quickly and accurately.Thus,the phylogenetic relationship between species and the taxonomic boundary between species were clarified,which effectively promoted the systematic taxonomic study of lichen of this genus.Based on the classical classification,this study applied the DNA-barcoding technology to the classification of the genus Physconia,constructed the phylogenetic tree of the genus with sequences such as ITS.Classified and identified the species of the genus Physconia in Hengduan mountain and surrounding areas in China.Identified and clarified 14 species of Physconia in the region,including 2 new species and 1 new record species in China.Morphological description,specimen citation,geographic distribution information statistics,morphological characterization,and key taxonomic characteristics were discussed for each species.The key of Physconia from Hengduan Mountain and adjacent region of China was compiled.