Phylogenetic and Taxonomic Analyses of Three New Wood-Inhabiting Fungi of Xylodon (Basidiomycota) in a Forest Ecological System

Wood-inhabiting fungi are a cosmopolitan group and show a rich diversity, growing in the vegetation of boreal, temperate, subtropical, and tropical regions. Xylodon grandineus, X. punctus, and X. wenshanensis spp. nov. were found in the Yunnan–Guizhou Plateau, China, suggested here to be new fungal species in light of their morphology and phylogeny. Xylodon grandineus is characterized by a grandinioid hymenophore and ellipsoid basidiospores; X. punctus has a membranous hymenophore, a smooth hymenial surface with a speckled distribution, and absent cystidia; X. wenshanensis has a grandinioid hymenophore with a cream to slightly buff hymenial surface and cystidia of two types. Sequences of the ITS and nLSU rRNA markers of the studied samples were generated, and phylogenetic analyses were performed using the maximum likelihood, maximum parsimony, and Bayesian inference methods. After a series of phylogenetic studies, the ITS+nLSU analysis of the order Hymenochaetales indicated that, at the generic level, six genera (i.e., Fasciodontia, Hastodontia, Hyphodontia, Lyomyces, Kneiffiella, and Xylodon) should be accepted to accommodate the members of Hyphodontia sensu lato. According to a further analysis of the ITS dataset, X. grandineus was retrieved as a sister to X. nesporii; X. punctus formed a monophyletic lineage and then grouped with X. filicinus, X. hastifer, X. hyphodontinus, and X. tropicus; and X. wenshanensis was a sister to X. xinpingensis.