Cortinarius qilianensis M. L. Xie, T. Z. Wei & Y. Li 2025, sp. nov.

Cortinarius qilianensis M.L. Xie, T.Z. Wei & Y. Li, sp. nov. MB 843750. Figs 3G, H, 6L, 7L. Etymology: The name refers to the type location, Qilian Mountain, a famous mountain in China. Typus: China, Gansu Province, Shandan County, Qilianshan National Nature Reserve, Yanzhishan Forest Park, in Picea forest, alt. 2800 m, 20 Aug. 2017, S.L. Wei (holotype HMJAU 44508). Pileus 15–80 mm diam., convex, later plane with a low umbo, incurved at the margin, surface viscid to somewhat glutinous in fresh condition, somewhat shiny to distinctly glittery when dry, not hygrophanous, orange white to greyish orange, paler at the margin. Lamellae emarginate, moderately crowded, purple to greyish violet when young, later brownish with violaceous tinges to brown, at first edges paler, even, then slightly serrate. Stipe 35–100 mm long, 9–26 mm thick, cylindrical at the upper part, clavate-bulbous at the base, up to 35 mm, surface with abundant yellowish white fibrillose, whitish with blue tinges at the apex when young, later yellowish, basal mycelium whitish. Universal veil yellowish, usually forming a sock like sheath on the stipe. Context fleshy, with marbled watery when moist, violet when young, especially at the upper stipe, later white with bluish tinges, somewhat hollow in stipe. Odour somewhat aromatic. Taste mild. Basidiospores 8.6–10.6 × 6.8–8.7 μm, Q = 1.09–1.43, Xav. = 9.0–9.5 × 7.0–7.7 μm, Qav. = 1.20–1.30, broadly ellipsoid to ellipsoid, rather weakly to moderately and densely verrucose, moderately dextrinoid. Basidia clavate, 4-spored, hyaline to subhyaline, rarely yellowish to yellowish brown. Lamellar edge fertile. Pileipellis duplex: epicutis well developed, hyphae loosely interwoven, hyaline to yellowish brown, 2–7 μm wide, smooth; hypocutis well developed, hyphae interwoven, 6–16 μm wide, hyaline, ± cylindrical, smooth. Clamp connections present. Ecology and distribution: Solitary or scattered in Abies and Picea forests. Known from Northwest China. Additional specimens examined: China, Gansu Province, Shandan County, Qilianshan National Nature Reserve, Yanzhishan Forest Park, in Picea forest, alt. 2800 m, 5 Sep. 2013, S.L. Wei, HMJAU 44510; ibid., 20 Aug. 2017, S.L. Wei, HMJAU 44509; Minle County, Qilianshan Nature Reserve, Dahekou, in Picea forest, alt. 2860 m, 9 Aug. 2018, M.L. Xie, HMJAU 48666; Xinjiang Uygur Autonomous Region, Shawan County, Lujiaowan, in Abies forest, alt. 2400 m, 8 Aug. 2019, M.L. Xie & P.S. Jia, HMJAU 48716. Notes: Cortinarius qilianensis is a phlegmacioid species, usually with robust and medium- to large-sized basidiomata. The pileus is usually viscid to somewhat glutinous in fresh condition, somewhat shiny to distinctly glittery when dry, with an odour that is somewhat aromatic, and the basidiospores are broadly ellipsoid to ellipsoid. Cortinarius qilianensis is similar to C. albocyaneus and C. lividomalvacus due to the shiny to distinctly glittery pileus. However, C. albocyaneus (e.g., Betula and Fagus) and C. lividomalvacus (Quercus) are associated with broadleaf trees, and the basidiomata of C. albocyaneus are slender (Dima et al. 2016, Eyssartier et al. 2017). The most closely related species of C. qilianensis is C. azureovelatus from which it differs by 15 substitutions and indel positions in nrITS region, with a similarity of 97.5 %.