Three new wood-inhabiting fungal species of Phanerochaetaceae (Polyporales, Basidiomycota) from Southwest China.

Three new wood-inhabiting corticioid fungal species from Southwest China, Phanerochaete albomarginata, P. nigella, and Rhizochaete membranacea, are proposed based on a combination of morphological features and molecular evidence. Phanerochaete albomarginata is characterized by membranaceous basidiomata, a monomitic hyphal system, generative hyphae with simple septa, tapering cystidia, and ellipsoid basidiospores. Phanerochaete nigella is characterized by its coriaceous basidiomata with a tuberculate hymenial surface, tubular cystidia, and ellipsoid basidiospores measuring 4.7-5.7 × 2.5-3.2 µm. Rhizochaete membranacea is characterized by membranaceous basidiomata, a monomitic hyphal system, generative hyphae encrusted with crystals, and ellipsoid basidiospores (4-5.5 × 2.7-3.1 µm). Phylogenetic analyses using Maximum likelihood (ML) and Bayesian inference (BI) were conducted based on ITS + nLSU markers. The resulting ITS + nLSU phylogram revealed that P. albomarginata formed a monophyletic lineage closely related to P. taiwaniana and P. yingjiangensis, while P. nigella formed a sister lineage to P. albida. Additionally, the phylogenetic tree of Rhizochaete inferred from the ITS + nLSU sequences showed that the new species formed a distinct branch and was sister to R. yunnanensis. This discovery enriches the known diversity of Phanerochaetaceae in subtropical Asia and further clarifies the phylogenetic relationships within the family.