Cylindrosporus flavidus gen. et comb. nov. (Hymenochaetales, Basidiomycota) segregated from Onnia

Onnia is one of the seven genera of Inonotus s.l., belonging to Hymenochaetaceae. According to the current concept, Onnia differs from the other six genera of Inonotus s.l. mainly by its either stipitate or sessile basidiocarps, duplex context, presence of hymenial setae and hyaline, thin-walled basidiospores. As the only species with sessile basidiocarps and cylindrical basidiospores in Onnia, O. flavida was transferred from Inonotus without molecular test. In this study, for the first time, Onnia flavida is included in nLSU- and ITS-based phylogenetic analyses. Phylogenetic analyses showed that Onnia flavida belonged to Hymenochaetaceae and was clearly separated from Onnia and other six genera of Inonotus s.l. Moreover, there is no other current genus in Hymenochaetaceae fit to accommodate this species from both morphological and phylogenetic perspectives. Therefore, a monotypic genus Cylindrosporus is newly proposed to accommodate the new combination C. flavidus. The distinct characters of Cylindrosporus that distinguish it from other morphologically and phylogenetically related genera are discussed.