Taxonomy,phylogeny And Biogeography Of Laetiporus(Polyporales,Basidiomycota)

Laetiporus is a genus of cosmopolitan brown rot fungi,some species of the genus are forest pathogens and some are edible with medicinal function,so it is an important group of macrofungi.During the last 100 years,comprehensive researches were carried out around the world,including morphological and phylogenetic studies.However,the taxonomical study of Laetiporus in China is lagged behind.In this paper,a systematic study on Laetiporus is presented to gain an insight into the species diversity,affinity and biogeography.In the present study,242 specimens from 11 countries were collected,including 207 from China and 35 from other parts of the world.Most of the specimens were collected from different forests in China by the author and deposited in the herbaria of BJFC and IFP.The remainders were made by loan from herbaria including HKAS,HMIGD,PDD,CFMR and PRM/JV.Fistly,the mophorlogical characters of the specimens were examined to identify the differences among diferent species.Then the affinities within the genus were verified based on multi-locus phylogeny including ITS,nrLSU,nrSSU,mtSSU,EF1-? and RPB2.Finally,The BEAST v1.8.0 and RASP v3.2 packages were used to furtherly inferred the historical biogeography of the genus Laetiporus.According to the morphological and molecular analyses,this study presents some progress:(1)eight Laetiporus species including four new species(Laetiporus ailaoshanensis,Laetiporus tibetica,Laetiporus xinjiangensis and Laetiporus zonatus)and one new Chinese record(Laetiporus sulphureus)are identified in China;(2)the thirteen Laetiporus species confirmed in this study are illustrated and a key is provided;(3)the phylogenetic relationships within this genus are inferred based on the Bayesian,Maximum Parsimony and Maximum Likelihood analyses,and six certain clustering tendencies are founded(Group I-VI);(4)the reconstruction and analysis of ancestral areas suggest that Laetiporus originated during the early Miocene(20.16±0.13 Mya)in temperate zones,and the combination of East Asia and North America has the highest probability(48%)of being the ancestral area;(5)six intercontinental dispersal routes are proposed:East Asia-eastern North America,North America-Central America-South America,East Asia-South Africa East Asia-Europe,North America-Europe and East Asia-Malay Archipelago-Australia-Hawaii.Further sampling and more molecular data are needed to furtherly clarify the species affinities within this genus around the world.