Taxonomy and Molecular Phylogeny of Phellodon (Thelephorales) with Descriptions of Four New Species from Southwest China

Abstract

Phellodon is a genus of ectomycorrhizal fungi belonging to the group known as the stipitate hydnoids. It is associated with coniferous trees in forest ecosystems and is widely distributed in the northern hemisphere. Phellodon, together with Hydnellum, and Sarcodon, is classified in the Bankeraceae, members of which are generally considered as symbiotic fungi. Ectomycorrhizal fungi can help plant roots fix nitrogen and improve the absorption capacity of soil nutrients by trees, so they play an important role in ecosystem protection. Taxonomic and phylogenetic studies of Chinese Phellodon collections were carried out. Four new Phellodon species were discovered from southwestern China based on a combination of morphological characters and molecular data. Phellodon atroardesiacus is characterized by the blackish blue to dark grey pileus, dark grey to ash grey spines, and presence of clamp connections in spines. Phellodon cinereofuscus is distinguished by a cottony tomentose pileal margin, long spines which become clay-buff when dry, and echinulate basidiospores. Phellodon stramineus is characterized by a depressed and tomentose pileus, straw buff-colored pileal surface, and dark grey to ash grey spines. Phellodon yunnanensis is distinguished by a clay-pink to brown pileus, pale brown to white spines, and the presence of clamp connections in the outer layer of stipe. Detailed descriptions, illustrations, and ecological traits for the new taxa are provided. Phylogenetic analyses inferred from the internal transcribed spacer (ITS) regions confirmed that the four new species are distinct within Phellodon.