Taxonomic and ecological significance of synnema-like structures/acanthophyses produced by <i>Physisporinus</i> (<i>Meripilaceae, Polyporales</i>) species

Abstract

Some species may cause butt rot in living Japanese cedars [Noguchi et al., 2007 (as Basidiomycete-B)], or establish mycorrhizal relationships with mycoheterotrophic orchids (Yamashita et al., 2020). Based on morphological and phylogenetic studies of aquatic fungi inhabiting wet wood in streams, we previously reported that five clades of fungi in the genus Physisporinus, i.e., two new species (P. microacanthophysis Shino, Sotome & Nakagiri and P. rhizomorphae Shino, Sotome & Nakagiri) and three unidentified groups (P. cf. 1 eminens, P. cf. 2 eminens, and P. cf. furcatus) form synnema-like structures (SSs) and produce numerous acanthophyses at their apices (Shino et al., 2022). Since cultures isolated from SSs or basidiocarps pro-duced several types of acanthophyses on agar media, we considered that these characters might be useful as a taxonomic trait of Physisporinus. However, our previous study did not examine whether genera that are closely related to Physisporinus also produce SSs/acanthophyses. Phylogenetically, Physisporinus is closely related to both Meripilus P. Karst.