Taxonomic reevaluation on Pyrrhoderma (Basidiomycota, Hymenochaetales) and reclassification of Pyrrhoderma species based on phylogenetic and type studies.

We reevaluated the species belonging to the genus Pyrrhoderma that were collected from Japan and Malaysia based phylogenetic analyses and morphological investigations. We found that Pyr. sendaiense is distinct from Pyr. adamantinum. Pyrrhoderma species with setal hyphae include Pyr. lamaoense, Pyr. noxium, Pyr. sublamaensis, and Pyr. williamsii. Pyrrhoderma noxium, synonymized with Pyr. sublamaense in earlier studies, was distinct from Pyr. sublamaense. All isolates from trees damaged by brown root rot were accommodated in the same clade with Pyr. noxium, and the cause of the disease was confirmed as Pyr. noxium. Pyrrhoderma williamsii resembles Pyr. lamaoense but is distinguished by a glabrous pileus surface and abundant hymenial setae. Fulvoderma species are similar to some Pyrrhoderma species but are distinguished by the duplex context separated by a thin crust composed of nonagglutinated hyphae. Some Inonotus species produce setal hyphae in the trama and context like some Pyrrhoderma species. However, the hyphae of these Inonotus species are acuminate at the tip, tapered toward the base, and often swollen toward the tip, whereas those of the Pyrrhoderma species are cylindrical and mostly equal. The following new combinations are proposed: Pyrrhoderma williamsii and Fulvoderma vallatum.