Taxonomic study on a threatened polypore, Polyporus pseudobetulinus, and a morphologically similar species, P. subvarius

A taxonomic study based on morphological and phylogenetic characters revealed that the specimens referred to as 'Polyporus pseudobetulinus' in Japan actually represent two distinct species, namely, P. pseudobetulinus and P. subvarius. These cam be distinguished by characteristics of the pileus surface, the presence/absence of clamp-connections on generative hyphae, and the shape of the basidiospores. P. subvarius is newly reported from Japan following the original description from China. The phylogenetic positions, detailed descriptions, and illustrations are provided for both species.