Septobasidium macrobasidium Q. Q. Jiang & C. L. Zhao 2024, sp. nov.

Septobasidium macrobasidium Q. Q. Jiang & C. L. Zhao sp. nov. Figs 3, 4 Holotype. China • Yunnan Province, Pu’er, Jingdong County, Wuliangshan National Nature Reserve, 24°29'17"N, 100°40'27"E, altitude: 1800 m a. s. l., on the living tree of angiosperm, leg. C. L. Zhao, 6 January 2019, CLZhao 9624 (SWFC). Diagnosis. Differs from other Septobasidium species by the coriaceous basidiomata with a cream surface, cylindrical basidia (48.5–83 × 6.5–13 µm), and thin-walled, narrowly cylindrical basidiospores with septa, measuring as 7–9 × 3.5–4.5 µm. Etymology. Macrobasidium (Lat.): refers to the larger basidia of the type specimen. Description. Basidiomata perennial, resupinate, easy to separate from substrate, coriaceous upon drying, up to 9 cm long, 5 cm wide, 2 mm thick. Hymenial surface smooth, slightly cream when fresh, cream upon drying. Sterile margin narrow, white to cream, up to 0.5 mm. Hyphal system monomitic, generative hyphae with simple septa, pale brown, thick-walled, frequently branched, interwoven. In section 850–1850 µm thick; subiculum pale brown, 30–80 µm thick; pillars brown, 350–550 µm high, 85–200 µm wide, hyphae of pillars 2–5 µm thick, hyaline or brown, forming 2–3 horizontal layers. Basidia arising directly from the generative hyphae, basidia cylindrical, straight, 4 - celled, 48.5–83 × 6.5–13 µm, colourless. Probasidia subglobose or ovoid, 13–23 × 7–20.5 µm, colourless, persistent. Haustoria consisting of irregularly coiled hyphae. Basidiospores narrowly cylindrical, colourless, thin-walled, with septa, (6.5 –) 7–9 (– 9.5) × (3 –) 3.5–4.5 (– 5) µm, L = 8.09 µm, W = 3.94 µm, Q = 1.55–2.83 (n = 60 / 2). Habitat and distribution. Growing on the plant Betulaceae Gray, associated with the insect of Diaspididae Ferris. Additional specimen examined (paratype). China • Yunnan Province, Pu’er, Jingdong County, Wuliangshan National Nature Reserve, 24°29'17"N, 100°40'27"E, altitude: 1800 m a. s. l., on the living tree of angiosperm, leg. C. L. Zhao, 6 January 2019, CLZhao 9658 (SWFC).