Abstract
The species diversity of Fomes in China has not been well studied, and all Fomes samples were previously identified as Fomes fomentarius based on morphology. Recent phylogenetic and morphological analyses on Fomes were carried out and one new species from Yunnan Province of southwest China, Fomes hengduanensis, was discovered. F. hengduanensis is characterized by perennial, pileate basidiomata with small ungulate pilei, greyish brown, fawn to dark grey, concentrically zonate and sulcate upper surface, greyish brown pore surface when fresh, distinct sterile margin, a trimitic hyphal system bearing clamp connections on generative hyphae, clavate to fusoid cystidioles, cylindrical basidiospores measuring 9.5–14 × 4.5–7 µm, and growing on Quercus semecarpifolia in montane forest. It differs from the most common species F. fomentarius by smaller basidiospores (9.5–14 × 4.5–7 µm vs. 15–21 × 5–7 µm), and also differs by the DNA sequences. We present the new species with illustrated description, molecular work and comparison with morphologically similar or related species.