Rediscovery and epitypification of Resupinatus merulioides (Resupinataceae, Agaricales) from its type locality in Japan

Resupinatus merulioides was originally described from Nikko, Tochigi Prefecture, Japan and characterized by its merulioid hymenophore. Since its description, no additional records have been reported from the type locality, and only a few records have been documented from other regions in Japan. Here, we report some new rediscoveries of R. merulioides from its type locality and other regions in Japan. Newly collected specimens were morphologically consistent with the original description. However, some fruiting bodies had different morphological characteristics such as variations in coloration. Molecular phylogenetic analyses revealed that Japanese specimens identified as R. merulioides formed a well-supported clade, and distinct from other species in this genus. Additionally, specimens labeled as R. merulioides from New Zealand formed a sister clade to R. merulioides s.s. and were genetically distinct. Because of newly observed morphological characters and DNA data, we designate an epitype based on the newly collected specimen from its type locality.