<i>Hypochnicium</i> sensu lato (<i>Polyporales</i>, <i>Basidiomycota</i>) from Japan, with descriptions of a new genus and three new species

Species of <i>Hypochnicium</i> (<i>Polyporales</i>, <i>Basidiomycota</i>) collected from Japan were studied on their taxonomy by morphological and phylogenetic approaches. Phylogenetic analyses based on a nrDNA LSU and ITS dataset including the Japanese specimens and other publicly available ones show that <i>Hypochnicium</i> is polyphyletic. Since the clade containing the type species <i>H. bombycinum</i> was well-supported, we defined this clade as <i>Hypochnicium</i> s. str., and emended <i>Hypochnicium</i> to include restricted taxa with only smooth basidiospores. The new genus <i>Neohypochnicium</i> is proposed to accommodate the remaining taxa excluded from the genus <i>Hypochnicium</i> s. str., which includes both species with smooth basidiospores and ornamented ones. Three new species, <i>Gyrophanopsis japonica</i>, <i>N. asiaticum</i> and <i>N. perlongicystidiosum</i> are described and illustrated based on morphological and phylogenetic analyses using an ITS region dataset. In addition, the following 15 new combinations are proposed: <i>N. albostramineum</i>, <i>N. aotearoae</i>, <i>N. capitulateum</i>, <i>N. cremicolor</i>, <i>N. cystidiatum</i>, <i>N. geogenium</i>, <i>N. guineense</i>, <i>N. huinayense</i>, <i>N. michelii</i>, <i>N. microsporum</i>, <i>N. patagonicum</i>, <i>N. pini</i>, <i>N. punctulatum</i>, <i>N. subrigescens</i> and <i>N. wakefieldiae</i>. An identification key to Japanese species of <i>Bulbillomyces</i>, <i>Gyrophanopsis</i>, <i>Hypochnicium</i> and <i>Neohypochnicium</i> is provided.