Meripilus noncontusus Y. C. Dai, Chao G. Wang & Yuan Yuan 2025, sp. nov.

Meripilus noncontusus Y. C. Dai, Chao G. Wang & Yuan Yuan sp. nov. Figs 22, 23 Etymology. Noncontusus (Lat.): refers to the species having pores without color changing when bruised. Diagnosis. Differs from other Meripilus species by resupinate basidiomata with a white pore surface when fresh, the absence of sterile margin, angular pores of 5–6 per mm, slightly thick-walled and apically encrusted hyphoid cystidia at the dissepiment edge, broadly ellipsoid to subglobose basidiospores measuring 5–5.5 × 4.2–4.7 µm. Type. CHINA • Guangdong Province, Guangzhou, Baiyunshan Forest Park, on fallen angiosperm trunk, 20 April 2023, Dai 24718 (BJFC 042272, holotype). Description. Basidiomata annual, resupinate, soft to ceraceous, and without odor or taste when fresh, becoming fragile upon drying, usually in small patches up to 2 cm long, 1 cm wide, and 0.7 mm thick at the center. Pore surface white to pinkish buff when fresh, unchanged after bruising, pinkish buff to buff yellow when dry; sterile margin absent; pores angular, 5–6 per mm; dissepiments thin, slightly lacerate. Subiculum pinkish buff, fragile, up to 0.2 mm thick. Tubes concolorous with pore surface, fragile when dry, up to 0.5 mm long. Hyphal system monomitic; generative hyphae simple septate, hyaline, smooth, IKI -, CB +; tissues unchanged in KOH. Subicular hyphae slightly thick-walled with a wide lumen, rarely branched, frequently simple septate, slightly flexuous, loosely interwoven, agglutinated, 5–8 µm in diam. Tramal hyphae slightly thick-walled with a wide lumen, occasionally branched, slightly flexuous, subparallel along the tubes, agglutinated, 3–6 µm in diam.; some slightly thick-walled hyphae at the dissepiment edge bearing crystals at tips and resembling hyphoid cystidia. Hymenial cystidia absent; cystidioles fusoid, thin-walled, smooth, 11–12 × 5.5–6 µm; basidia barrel-shaped to capitate, with four sterigmata and a simple basal septum, 12–14 × 6.5–8 µm; basidioles of similar shape to basidia, but smaller. Basidiospores broadly ellipsoid to subglobose, hyaline, thin-walled, smooth, with one medium guttule, IKI -, CB -, (4.8 –) 5–5.5 (– 5.6) × (4 –) 4.2–4.7 (– 4.8) µm, L = 5.13 µm, W = 4.45 µm, Q = 1.15 (n = 30 / 1). Notes. In our phylogenetic analyses, Meripilus noncontusus is closely related to the erubescent species complex of Meripilus, viz., M. furcatus (Núñez & Ryvarden) Westph. & Rajchenb., M. rhododendri (Y. C. Dai, Yuan Yuan & Chao G. Wang) Westph. & Rajchenb., M. sanguinolentus (Alb. & Schwein.) Rajchenb. & Westph., M. subfurcatus (Y. C. Dai, Yuan Yuan & Chao G. Wang) Westph. & Rajchenb. and M. yunnanensis (C. L. Zhao) Westph. & Rajchenb., and these species nested in a joint subclade (Fig. 2). They all have a white pore surface when fresh, but the first three species have an erubescent pore surface when bruised. Meripilus furcatus differs from M. noncontusus by thin-walled and forked hymenial cystidia; M. yunnanensis also has thin-walled hyphoid cystidia at the dissepiment edge, but it has bigger pores (2–3 per mm vs. 5–6 per mm, Cai et al. 2023). Morphologically, Meripilus emarginatus is similar to M. noncontusus, sharing ceraceous white basidiomata without color change after being bruised and almost the same size of angular pores (6–7 per mm in M. emarginatus, 5–6 per mm in M. noncontusus, this study). However, M. emarginatus has thin-walled smooth hymenial cystidia and distinctly thick-walled hyphoid cystidia bearing coarse crystals.