Hymenochaete bannaensis Y. L. Deng & C. L. Zhao 2025, sp. nov.

Hymenochaete bannaensis Y. L. Deng & C. L. Zhao sp. nov. Figs 5, 6, 7 Holotype. China • Yunnan Province, Xishuangbanna, Wild elephant Valley, GPS coordinates: 22°17'N, 100°85'E, altitude 900 m asl., on the dead bamboo, leg. C. L. Zhao, 25 January 2024, CLZhao 35721 (SWFC). Etymology. Bannaensis (Lat.): referring to the locality (banna) of the type specimen. Diagnosis. Hymenochaete bannaensis is characterized by the flocculent basidiomata with cinnamon to yellowish brown to rust-brown hymenial surface, generative hyphae with simple septa and broadly ellipsoid to globose basidiospores. Description. Basidiomata annual, resupinate, closely adnate, flocculent, without odor or taste when fresh, up to 7 cm long, 3.5 cm wide, and 200 μm thick. Hymenial surface smooth, cinnamon to yellowish brown when fresh, yellowish brown to rust-brown upon drying. Sterile margin yellowish brown, thinning out, up to 2 mm. Hyphal system monomitic; generative hyphae with simple-septa, brown, thick-walled, smooth, moderately branched, 2.4–2.9 µm in diameter, IKI –, CB –, tissues darkening in KOH; subhymenial hyphae densely covered by crystals. Cystidia and cystidioles absent. Basidia subcylindrical, colorless, thin-walled, with four sterigmata and a basal simple septum, 18.5–23 × 3.5–4 µm; basidioles numerous, in shape similar to basidia but smaller. Setae abundant, distinctly thick-walled, subulate, with an acute tip, yellowish to reddish brown, 67–94 × 7–11 µm, projecting out of the hymenium up to 33–44.5 µm. Basidiospores broadly ellipsoid to globose, colorless, thin-walled, smooth, always filled with oil drop, CB –, (3.6 –) 3.7–4 (– 4.1) × (3.4 –) 3.5–3.9 (– 4) µm, L = 3.87 µm, W = 3.67 µm, Q = 1.05–1.06 (n = 60 / 2). Another specimen (paratype) examined. China • Yunnan Province, Xishuangbanna, Wild elephant Valley, GPS coordinates: 22°17'N, 100°85'E, altitude 900 m asl., on the fallen angiosperm branch, leg. C. L. Zhao, 25 January 2024, CLZhao 35884 (SWFC). Notes. Phylogenetically, Hymenochaete bannaensis is nested as sister to H. muroiana with strong supports (100 / 100 / 1.00) based on ITS + nLSU sequences (Figs 1, 2). Morphologically, H. muroiana is different from H. bannaensis by the brun suie basidiomata, smaller ellipsoid to subcylindrical basidia (8–10 × 3 µm) and narrower ovoid to ellipsoid basidiospores (3.5–4 × 2–2.6 µm; Léger 1998). Hymenochaete acerosa S. H. He & Hai J. Li, H. cystidiata Parmasto and H. sinensis Y. C. Li & C. L. Zhao, are similar to H. bannaensis by thick-walled and acute setae. However, H. acerosa is distinguished from H. bannaensis by its effused and detachable basidiomata, longer setae (85–170 × 5–8 µm), wider clavate basidia (13–21 × 5–8 µm) and larger basidiospores (7–8.5 × 4.8–6 µm; He and Liu 2011). Furthermore, H. cystidiata differs from H. bannaensis by its longer setae (60–100 × 7–10 µm), and subcylindrical basidiospores (4.8–5.8 × 2.5–3.2 µm; Parmasto 2012). Moreover, H. sinensis differs from H. bannaensis by having ceraceous basidiomata, coconut brown to brownish black hymenial surface, shorter barrel-shaped basidia (10–12 × 3.1–3.8 µm) and longer ellipsoid to broadly ellipsoid basidiospores (4–5 × 2.5–3.5 µm; Li et al. 2024).