<i>Chionobium takahashii</i>, gen. et sp. nov., associated with snow blight of conifers in Japan

<i>Gremmenia abietis</i> (Dearn.) Crous (syn: <i>Phacidium abietis</i>) was originally described in North America to accommodate the species associated with snow blight of <i>Abies</i> and <i>Pseudotsuga</i> spp. In Japan, this species was first observed on the dead needles on <i>Abies sachalinensis</i> and <i>Picea jezoensis</i> var. <i>jezoensis</i> in 1969. However, the identity of Japanese species was unclear due to the lack of molecular data and the absence of anamorph description. In this study, we collected fresh specimens from various conifer species (<i>A. sachalinensis, A. veitchii, Pic. jezoensis</i> var. <i>jezoensis, Pic. jezoensis</i> var. <i>hondoensis, Pinus koraiensis</i>, and <i>Pin. pumila</i>) in Japan and revised the taxonomy based on morphological and phylogenetic analyses. Phylogenetic analyses based on nuc rDNA internal transcribed spacer ITS1-5.8S-ITS2 (ITS), nuc 28S rDNA (28S), and RNA polymerase II second largest subunit (<i>RPB2</i>) regions indicated that the species belongs to Phacidiaceae. Conidiomata formed in vitro produced pyriform, hyaline conidia without mucoid appendage, which distinguished the species from phylogenetically related genera. Consequently, we established <i>Chionobium takahashii</i> to accommodate the snow blight fungus in Japan. Further phylogenetic analyses also indicated that <i>C. takahashii</i> includes several distinct clades corresponding to the host genera (<i>Abies, Picea, Pinus</i>). Morphological differences among those clades were unclear, suggesting that <i>C. takahashii</i> may contain host-specific cryptic species.