A Preliminary Study On Taxonomy Of Skeletocutis

Skeletocutis is an important group of wood-decaying fungi,and has a wide distribution in the world.The genus belongs to the family of Incrustoporiaceae,and causes a white rot of wood.Most species of the genus grow on fallen branches,fallen trunk,rotten wood and stumps of trees,and some of them grow on other fungi.Up to now,71 species of the genus have been reported worldwide.Because its classification characteristics are vague and difficult to distinguish from other related genera,the species within the genus have undergone many changes and modifications.Since the establishment of genus,many species have been combined in the genus,and some were removed out of the genus.In this study,both molecular phylogeny and morphology were used to classify species of Skeletocutis.Based on more than 500 specimens of the study,23 species of Skeletocutis are found,and their detailed descriptions are provided,and microstructure drawings were supplied to compare the differences between similar species,and a key to the Chinese species of Skeletocutis is given.The sequences of ITS and n LSU genes of species in the genus were amplified for phylogenetic study.In this study,two new species of Skeletocutis were found: Skeletocutis subalbomarginata and S.vietmanensis.The fruiting bodies of S.subalbomarginata is reddish brown with a cap and the simple septa in generative hyphae,and its basidiospores are narrowly allantoid.Abundant hyphal pegs present in the hymenium of S.vietmanensis,and its basidiospores are pear-shaped to ovoid-shaped.These two new species can be distinguished from other species in the genus.Three combinations: Skeletocutis albomarginata,S.indica and S.sajanensis,are proposed.The morphological characteristics of these three species are consistent with Skeletocutis,and they are always nested in Skeletocutis clade in phylogenetic analysis,so these three species are combined in Skeletocutis.Morphological structure examination and phylogenetic analysis demonstrate that Skeletocutis is a polyphyletic group.The genus is charactrized by basidiocarps annual to perennial,resupinate to pileate,pore surface white,cream,pink,lavender to reddish brown,pores small,a dimitic hyphal structure with the generative hyphae covered by sharp-pointed crystals,and hyaline,thin-walled,tiny basidiospores with negative reactions in Melzer's reagent and Cotton Blue.