Taxonomic reevaluation on <i>Pyrrhoderma</i> (<i>Basidiomycota</i>, <i>Hymenochaetales</i>) and reclassification of <i>Pyrrhoderma</i> species based on phylogenetic and type studies

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