First record of Inonotus pachyphloeus (Hymenochaetaceae) from the Japanese mainland

Abstract

Inonotus pachyphloeus (Pat.) T. Wagner & M. Fisch. (Hymenochaetaceae) is a rare perennial polypore fungus that has previously been reported in Japan only from evergreen broad-leaved forests on Ishigaki and Iriomote Islands, with the Yaeyama Islands considered to represent the northern limit of its distribution. In this study, basidiomata of I. pachyphloeus were recorded in December 2023 in a coastal evergreen broad-leaved forest in Hyuga City, Miyazaki Prefecture, eastern Kyushu, Japan. The basidiomata occurred on the trunk and fallen branches of a single Machilus thunbergii tree and were identified as I. pachyphloeus based on their morphological characteristics. This record represents the first occurrence of this species on the Japanese mainland and significantly extends the known northern limit of its distribution in Japan.