Morphological and molecular identification of two new wood-inhabiting species of Hyphoderma (Basidiomycota) from Qinghai, northwestern China.

Wood-inhabiting fungi serve as primary decomposers of lignocellulose in forest ecosystems, facilitating carbon release and nutrient turnover. These processes are essential for sustaining material cycling, energy flow, and soil health. The genus Hyphoderma, within the Basidiomycota, is a notable group among wood-inhabiting fungi. This study introduces two new resupinate, adnate, wood-inhabiting fungal taxa, Hyphoderma tenuicystidiatum and H. tabuliformis, based on morphological and molecular phylogenetic analyses. Hyphoderma tenuicystidiatum is distinguished by light vinaceous gray fresh basidiomata with a smooth hymenophore, a monomitic hyphal system with clamp connections on generative hyphae, cylindrical cystidia, the presence of fusoid cystidioles, and subcylindrical to cylindrical basidiospores measuring 10.4-14.9 × 5.2-7.1 µm. In contrast, H. tabuliformis exhibits white to cream fresh basidiomata with an arachnoid hymenophore, encrusted generative hyphae, clavate cystidia, and subcylindrical basidiospores measuring 8.7-12.2 × 3.6-4.2 µm. The discovery of two new species in Qinghai enriches the diversity of Hyphoderma and provides additional morphological and molecular data for the genus.