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

Cortinarius coriaceus Zhu L. Yang, Liu K. Jia & Zi R. Wang sp. nov. Fig. 3 Etymology. The epithet “ coriaceus ” (Lat.) refers to the brown pileus with a leathery texture of this species. Holotype. China • Yunnan Province: Lijiang City, Yulong Naxi Autonomous County, Lijiang Alpine Botanical Garden, in a subalpine temperate broad-leaved and coniferous mixed forest with trees of Quercus and Pinus, 27°0.21'N, 100°10.71'E, elevation 3,340 m, 7 August 2023, Dong-Mei Li 299 (KUN-HKAS 145316). GenBank: ITS: PQ 772202, nrLSU: PQ 772214. Diagnosis. Cortinarius coriaceus looks like C. odoritraganus Niskanen, Liimat. & Ammirati, but differs in its emarginate lamellae, cylindrical stipe, and relatively larger basidiospores (Niskanen 2020). Description. Basidioma medium-sized to large. Pileus 3 cm diam when young, 4.5–7 cm diam when mature, initially slightly campanulate, becoming plano-convex, occasionally with slightly subumbonate center, viscid, with a leathery texture; brown (6 C 4–6 C 7), paler (6 A 2–6 A 4) towards the center, covered with white (1 A 1) fibrillose squamules when young; pale brown to brown (6 A 4–6 C 4), pale brown (6 A 2), or dark brown (6 D 4–6 D 6) towards the center when mature; margin incurved, with innate radial brownish (6 C 2–6 C 3) stripes when young; context of pileus pale brown to brown (6 A 3–6 B 3, 6 C 6). Lamellae emarginate, medium-spaced (L = 38–52, l = 27–36), pale brown (6 A 4) with a faint pinkish (12 A 2) tint when young, later brown (6 C 4–6 C 7). Stipe 4.5–6 × 0.7–1.2 cm, cylindrical, dirty white (1 A 1–1 B 1) and pale violaceous (16 A 2–16 A 4), with more and more violaceous (16 A 4) tint towards the stipe apex when young, later dirty white (1 A 1–1 B 1), pale brown (6 B 2–6 B 4), covered with brown (6 C 6) to dark brown (6 D 6) fibrillose squamules; annulus cortinate; context of stipe dirty white (1 A 1–1 B 1) with brown (6 C 6); basal mycelium white (1 A 1). Basidiospores [60 / 3 / 3] (10 –) 11.5–12.5 (– 14) × (5 –) 7.5–10 μm, Q = 1.25–1.43 (– 1.66), av. = 12.06 ± 0.85 × 8.33 ± 1.48 μm, Qav. = 1.48 ± 0.24, ellipsoid to amygdaliform, moderately to strongly verrucose, inamyloid. Basidia 37.5–43 × 7.5–10 μm, 4 - spored, clavate. Trama of lamellae regular, composed of colorless to yellowish, smooth hyphae 12.5–15 μm wide. Cystidia absent. Pileipellis duplex: epicutis weakly developed, 15–20 μm thick, composed of only 2–3 layers of interwoven to parallel, colorless, smooth, thin-walled, long-celled hyphae 3–7.5 µm wide; hypocutis composed of interwoven to parallel, colorless, cylindrical, thin-walled hyphae 12.5–17.5 μm wide. Clamp connections common in all parts of basidioma. Habitat / host. Summer. Solitary or gregarious on soil in subalpine temperate broad-leaved and coniferous mixed forests with trees of Quercus and Pinus. Distribution. Currently known from southwestern China. Additional specimens examined. China • Yunnan Province: Lijiang City, Yulong Naxi Autonomous County, Lijiang Alpine Botanical Garden, in a subalpine temperate broad-leaved and coniferous mixed forest with trees of Quercus and Pinus, 27°0.21'N, 100°10.71'E, elevation 3,340 m, 7 August 2023, Guan-Rui Li 328 (KUN-HKAS 145314), same place and date, Guan-Rui Li 333 (KUN-HKAS 145315). Notes. Cortinarius coriaceus is characterized by its brown, leathery-wrinkled pileus, pinkish-tinted lamellae, and relatively larger basidiospores. Cortinarius coriaceus is phylogenetically closely related to and morphologically similar to C. odoritraganus, known from Eastern North America and Costa Rica, in mixed temperate forest with Abies and Betula or mountain Quercus forest. However, C. odoritraganus differs in its paler pileus, adnexed, purple-brown to brown lamellae, longer and thicker stipe (5–10 × 1–2 cm), and relatively smaller basidiospores (9.5–11.5 × 6–7.5 μm) (Niskanen 2020). Cortinarius niveotraganus Kytöv., Niskanen & Liimat., another related species, is distinguished by its hemispherical to broadly convex pileus, initially white to greyish white lamellae with bluish tints, clavate stipe, relatively smaller basidiospores (8.6–10.9 × 5.2–6.3 μm), and occurrence in planted Betula forests (Niskanen 2014).