Cortinarius xizangensis T. Z. Wei, M. L. Xie & Y. Li 2025

Cortinarius xizangensis T.Z. Wei, M.L. Xie & Y. Li, sp. nov. MB 843755. Figs 5G, H, 6T, 7T. Etymology: The name refers to the type location, Xizang Autonomous Region, China. Typus: China, Xizang Autonomous Region, Milin County, Nanyigou, under Abies and Pinus, alt. 3166 m, 20 Sep. 2015, B.B. Li & T.Z. Wei (holotype HMAS 274227). Pileus 20–55 mm diam., convex when young, later plane to convex with rounded umbo, margin somewhat wavy, surface somewhat viscid and strongly hygrophanous when moist, at first with white fibrillose, especially at the margin, violet brown at margin, orange red at the centre. Lamellae emarginate, moderately crowded, greyish violet when young, later greyish orange to brown, edges even. Stipe 20–80 mm long, 5–7 mm thick, cylindrical to subcylindrical, slightly thickened at base, up to 12 mm, surface white fibrillose, bluish tinges at the apex. Universal veil white, sometimes forming a thin ring on the stipe. Context fleshy, bluish tinges, especially at the stipe apex. Odour and Taste not recorded. Basidiospores 7.1–9.0(–9.5) × 5.7–7.3 μm, Q = 1.10–1.38, Xav. = 7.6–8.2 × 6.3–7.0 μm, Qav. = 1.21–1.28, subgloboid to broadly ellipsoid, finely to moderately verrucose. Basidia clavate, 4-spored, hyaline to subhyaline, rarely yellowish to yellowish brown. Lamellar edge fertile. Pileipellis duplex: epicutis well developed, hyphae interwoven, hyaline to yellowish brown, 3.5–10 μm wide, smooth or with encrusted spots; hypocutis well developed, hyphae 15–34 μm wide, hyaline, somewhat cellular. Clamp connections present. Ecology and distribution: Scattered or gregarious in alpine coniferous forests of Abies and Pinus or mixed Abies dominated forests with Cupressus, Quercus, Rhododendron and Rosa. Known from Xizang of China. Additional specimens examined: China, Xizang Autonomous Region, Bomi County, alt. 3246 m, 21 Sep. 2014, Q.M. Wang & W.L. Lu, HMAS 272517; Milin County, Nanyigou, in Abies dominated forest with Quercus, Rhododendron and Rosa, alt. 3166 m, 20 Sep. 2015, T.Z. Wei & B.B. Li, HMAS 254260, HMAS 254261, HMAS 254415, HMAS 274219, HMAS 274980, HMAS 275038; Yadong County, Naiduila, in Abies dominated forest with Cupressus, Rosa and Rhododendron, alt. 3956 m, 14 Sep. 2015, T.Z. Wei & B.B. Li, HMAS 275210. Notes: Cortinarius xizangensis is characterized by a reddish brown and strongly hygrophanous pileus, a whitish universal veil, and subgloboid to broadly ellipsoid basidiospores. The nrITS sequence of the holotype differs from other known members of sect. Anomali by at least 32 substitutions and indel positions. Phylogenetically, C. xizangensis is close to C. anomalus and C. subanomalus. However, the pileus of C. anomalus is usually weakly hygrophanous and the basidiospores are larger, with dimensions of 8.0–9.0(–9.5) × (5.5–)6.0–7.0 μm (Dima et al. 2016). Cortinarius subanomalus has a violet veil, subgloboid basidiospores, and occurs in Quercus aquifolioides forests.