Cortinarius brunneoverrucosus Zhu L. Yang, Liu K. Jia & Zi R. Wang 2025, sp. nov.

Cortinarius brunneoverrucosus Zhu L. Yang, Liu K. Jia & Zi R. Wang sp. nov. Fig. 2 Etymology. The epithet “ brunneoverrucosus ” (Lat.) refers to the pileus with brown verrucose squamules of this species. Holotype. China • Yunnan Province: Pu’er City, Jingdong Yi Autonomous County Ailao Mountain Subtropical Forest Ecosystem Research Station, Chinese Academy of Sciences, in a subtropical broad-leaved forest with trees of Lithocarpus, 24°32.57'N, 101°1.62'E, elevation 2,491 m, 23 July 2013, Yang-Yang Cui 32 (KUN-HKAS 79712). GenBank: ITS: PQ 772212, nrLSU: PQ 772224. Diagnosis. Cortinarius brunneoverrucosus is sister to C. corrugatus Peck but differs by its yellowish brown to brown pileus with brown verrucose squamules, more robust stipe, relatively wider basidiospores, and exclusive occurrence in subtropical broad-leaved forest with trees of Lithocarpus and Quercus (Peck 1872; Phillips 2010; Kuo 2020). Description. Basidioma large. Pileus 8–10.5 cm diam, hemispherical, viscid, verrucose; yellow-brown to brown (5 B 7–5 C 7), darker towards the center (5 D 8), paler towards the margin (5 B 3–5 B 5); covered with brown (5 C 7) to dark brown (5 D 8–5 E 8) verrucose to floccose squamules; margin with innate radial stripes, occasionally with pale yellow (4 A 2) floccose squamules; context of pileus white (1 A 1). Lamellae adnate with decurrent tooth, crowded (L = 64–73, l = 33–38), pale brown (6 A 2–6 A 4) with a faint pale pinkish (12 A 2) tint. Stipe 8.5–18 × 1.2–2 cm, tapering upwards, pale brown (6 A 2–6 A 4) to pale yellow (3 A 2–3 A 4), covered with brown (6 C 4) to orange-brown (5 A 8) fibrillose squamules; context of stipe white (1 A 1); basal mycelium white (1 A 1) with a faint pale pinkish (12 A 2) tint. Basidiospores [60 / 2 / 2] (12.5 –) 15–16.5 (– 17.5) × (10 –) 11.5–12.5 (– 15) μm, Q = 1.2–1.5 (– 1.75), av. = 15.64 ± 1.61 × 12.31 ± 1.48 μm, Qav. = 1.27 ± 0.12, broadly ellipsoid to broadly amygdaliform, strongly verrucose, inamyloid. Basidia 37.5–50 × 7.5–10 μm, 4 - spored, clavate. Trama of lamellae regular, composed of colorless to yellowish, smooth hyphae 10–12.5 μm wide. Cystidia absent. Pileipellis duplex: epicutis weakly developed, 12–15 μm thick, composed of only 3–5 layers of interwoven to parallel, colorless to yellowish, smooth, thin-walled, long-celled hyphae 2.5–4 µm wide; hypocutis composed of parallel, colorless to yellowish brown, cylindrical, thin-walled hyphae 12.5–20 μm wide. Clamp connections common in all parts of basidioma. Habitat / host. Summer to autumn. Solitary on soil in subtropical broad-leaved forests with trees of Fagaceae. Distribution. Currently known from southwestern China. Additional specimen examined. China • Yunnan Province: Pu’er City, Jingdong Yi Autonomous County, Ailao Mountain Subtropical Forest Ecosystem Research Station, Chinese Academy of Sciences, in a subtropical broad-leaved forest with trees of Quercus, 24°32.57'N, 101°1.62'E, elevation 2,424 m, 8 October 2021, Jian-Wei Liu 2440 (KUN-HKAS 145321). Notes. Cortinarius brunneoverrucosus is characterized by its hemispherical, viscid, verrucose pileus, pale brown lamellae with a slightly pale pinkish tint, and relatively larger, broadly ellipsoid to ellipsoid basidiospores. Cortinarius brunneoverrucosus is sister to C. corrugatus Peck, originally described from the highlands in the United States, under Aalmia latifolia, but C. brunneoverrucosus is only found in subtropical China, under trees of Lithocarpus or Quercus. Moreover, C. corrugatus differs from C. brunneoverrucosus by its convex to broadly convex pileus with distinctively corrugated-wrinkled, thinner stipe, amygdaliform, relatively narrower basidiospores (12–15 × 8–10 μm) (Peck 1872; Phillips 2010; Kuo 2020). Cortinarius brunneoverrucosus belongs to sect. Dulciolentes Soop, a small section that has previously included only seven species, mainly distributed in Australia, inhabiting forests with Fagaceae, Nothofagaceae, and Myrtaceae (Soop et al. 2019). However, excluding C. corrugatus, which is from North America and is agaricoid, as mentioned earlier, three other species from Oceania, C. peraurantiacus Peintner & M. M. Moser, C. pisciodorus (E. Horak) Peintner & M. M. Moser, and C. dulciolens E. Horak, M. M. Moser, Peintner & Vilgalys, are all sequestrate (Moser 1983; Peintner et al. 2002 a, 2002 b; Soop et al. 2019). The discovery of C. brunneoverrucosus represents the first species of sect. Dulciolentes in China and the second agaricoid taxon within the section.