Taxonomic study of Favolus and Neofavolus gen. nov. segregated from Polyporus (Basidiomycota, Polyporales)

We present a taxonomic study of 'group Favolus' and related species in Polyporus. Phylogenetic analyses of nurLSU and ITS regions revealed that the infrageneric 'group Favolus' is divided into two main clades. Fungi within the group share laterally stipitate basidiocarps, with non-crustose stipe surfaces, and are distinguishable by the morphology of the pileus surface. One clade is characterized by species with hyaline to brown cutis, composed of hyaline to brown agglutinated generative hyphae. The other clade accommodates species with radially striate pileus, and lacks any distinct cutis of agglutinated hyphae. We propose Neofavolus gen. nov., typified by N. alveolaris, for the former clade, and revise the genus Favolus, typified by F. brasiliensis, for the latter clade. Neofavolus includes N. mikawai and N. cremeoalbidus sp. nov., known only from temperate eastern Asia, in addition to N. alveolaris. Favolus includes members of the Polyporus grammocephalus complex, the P. tenuiculus complex, and P. pseudobetulinus. We reveal that the polypore known as 'P. grammocephalus' in Asia includes F. acervatus and F. emerici (= P. grammocephalus), whereas 'P. tenuiculus' includes three distinct species; F. brasiliensis from tropical America, and F. spathulatus and F. roseus from tropical Asia. Detailed descriptions and illustrations are provided for the accepted species in Favolus and Neofavolus.