Taxonomy And Phylogeny Of Vararia And Related Genera In China

Vararia is very rich in species diversity and mainly distributes in tropics and subtropics.Morphologically,it is similar to Asterostroma,Baltazaria,Dichostereum and Scytinostroma by sharing dextrinoid skeletal hyphae,and all of them are phylogenetically placed in Peniophoraceae(Russuales,Basidiomycota).So far,many taxa have been described from Europe,America and Africa but no comprehensive research has been carried out in China.Meanwhile,most of the described species in Vararia and related genera have not been sequenced and phylogenetically analysed.Previous phylogenetic studies showed that Vararia and Scytinostroma were not monophyletic and the genetic delimitation between Vararia and its related genera were vague.Therefore,in order to establish and improve a natural and reasonable taxonomic system of Vararia and its related genera,it is necessary to carry out comprehensive taxonomic and phylogenetic studies by a extensive sampling.About 490 specimens of the five corticoid fungi genera mentioned above are studied based on morphological features,substarate,geographical distribution of each species and phylogenetic analyses.The studied materials,were mostly collected from the different areas of China,and deposited in the herbarium of Beijing Forestry University(BJFC).Some specimens were loaned from the Center for Forest Mycology Research,U.S.Forest Service(CFMR).The Bayesian and Maximum Likelihood analyses were used for constructing phylogenetic trees based on two separated datasets of ITS+nrLSU and ITS+nrLSU+mtSSU+EF1-?.The main results and conclusions of this study are as follows:(1)The genera Dichostereum and Asterostroma are monophyletic,but Vararia and Scytinostroma are highly polyphyletic.(2)The molecular phylogenetic analyses indicate that traditional Vararia and Scytinostroma,including Baltazaria newly established in 2018,cluster into 23 well supported clades.Except core clades of the three genera,each lineage is a potential new genus.(3)Twenty-six new species,including Dichostereum austrosinense,D.boidinii,D.eburneum,Vararia bispora,V montana and 21 unpublished species are discovered.Vararia amphithallica,V.breviphysa,V.cinnamomea and V sphaericospora are new to China.In this study:(1)keys to all the genera and species;(2)detailed and illustrated descriptions of all the 39 species;(3)scanning electron micrographs(SEM)of ornamented basidiospores of Asterostroma and Dichostereum species are given.Reliable characteristics of Vararia sensu stricto and Scytinostroma sensu stricto are discussed.Vararia sensu stricto differs from other related genera by its yellow soft basidiocarps,generative hyphae with clamps,dextrinoid skeletal hyphae with straight and stiff branches and smooth fusoid basidiospores with or without amyloid suprahilar plage.Scytinostroma sensu stricto differs from other related genera by its pale yellowish to ochraceous basidiocarps,generative hyphae without clamps,dextrinoid binding hyphae less branched in hymenial surface and smooth ellipsoid to reniform amyloid basidiospores.The shape of skeletal hyphae,ornamentations of basidiospore wall,shape and size of basidiospores,generative haphae with or without clamps,and sulphobenzaldehyde reaction of gloeocystidia are regarded as important taxonomy features for idetification at generic and species level.