Two new species of Tomentella (Thelephorales, Basidiomycota) from Lesser Xingan Mts., northeastern China

Two new species of Tomentella from the Lesser Xingan Mts. of northeastern China, T. pallidocastanea and T. tenuirhizomorpha, are described and illustrated using morphological characteristics and molecular phylogenetic analysis. T. pallidocastanea is characterized by mucedinoid basidiocarps adherent to the substrate, a light reddish brown to pinkish grey hymenophoral surface, absence of rhizomorphs and cystidia, generative hyphae with clamps, rarely with simple septa and echinulate, and subglobose to lobed basidiospores (echinuli up to 1.5 μm long). T. tenuirhizomorpha is characterized by mucedinoid basidiocarps separable from the substrate, a greyish brown to dark brown hymenophoral surface, thin rhizomorphs in the subiculum and margins, an absence of cystidia, generative hyphae with clamps rarely with simple septa and echinulate, and subglobose to globose basidiospores (echinuli up to 1.5 μm long). Molecular analyses using Maximum Likelihood, Maximum Parsimony and Bayesian Analysis confirm the phylogenetic position of the two new species. The discriminating characters of these two new species and their closely related species are discussed in this study.