Cortinarius rufolilacinus M.L. Xie, T.Z. Wei & Y. Li, sp. nov. MB 843752. Figs 4C, D, 6N, 7N.

Etymology: The name refers to the reddish lilac pileus.

Typus: China, Xizang Autonomous Region, Linzhi City, Sejila Mountain, in Abies georgei var. smithii forest with Rhododendron, alt. 4120 m, 5 Sep. 2020, M.L. Xie (holotype HMJAU 48739).

Pileus 35–64 mm diam., at first convex, later plane to plano-convex, margin sometimes incurved and wavy, surface weakly hygrophanous when moist, innately fibrillose, pale violet universal veil remnants at first, especially at the margin, dull reddish lilac when young, finally brownish orange to slightly brown. Lamellae emarginate, moderately crowded, greyish violet when young, later bluish grey to brown, edges even. Stipe 80–120 mm long, 8–11 mm thick, cylindrical to subcylindrical, slightly thickened at the base, surface violet fibrillose when young, later becoming greyish brown at the middle part, basal mycelium white to pale bluish. Universal veil copious, pale violet at first, flocculose-fibrous, forming fibrils on the pileus and sock like sheath on the stipe, latter yellowish. Context fleshy, whitish when young, marbled watery at the pileus when moist, with bluish tinges, especially at the upper part and base of stipe, becoming yellowish at the middle part of stipe, finally yellowish brown. Odour radish. Taste not recorded. Basidiospores 7.7–10.1 × 6.1– 7.9 μm, Q = 1.13–1.31, Xav. = 8.4–8.9 × 6.8–7.2 μm, Qav. = 1.22–1.25, subgloboid to broadly ellipsoid, moderately verrucose, moderately to rather strongly dextrinoid. Basidia clavate, 4-spored, hyaline to subhyaline, rarely yellowish to yellowish brown. Lamellar edge fertile. Pileipellis duplex: epicutis well developed, hyphae interwoven, slightly yellowish brown to brown, 4–14 μm wide, slightly encrusted; hypocutis well developed, hyphae 12–25 μm wide, hyaline to slightly yellowish brown, somewhat cellular, smooth. Clamp connections present.

Ecology and distribution: Solitary to gregarious in Abies georgei var. smithii forests with Rhododendron. Known from Tibetan Plateau of China.

Additional specimens examined: China, Xizang Autonomous Region, Linzhi City, Sejila Mountain, in Abies georgei var. smithii forest with Rhododendron, 24 Jul. 2013, S.R. Wang, HMJAU 48747; ibid., 4 Aug. 2013, HMJAU48745, HMJAU48746.

Additional nrITS sequences data from public sequence repositories: China, KU836522, ZJ0003SMJ01 as C. caninus in GenBank.

Notes: Cortinarius rufolilacinus is characterized by medium-sized basidiomata, a reddish lilac and weakly hygrophanous pileus, and a violet universal veil. The most closely related species of C. rufolilacinus is C. robustianomalus from which it differsbyfivesubstitutionsandindelpositions.Morphologically, compared with C. rufolilacinus, C. robustianomalus has an olive tinged pileus, a more robust stipe, a greyish universal veil, and rather round basidiospores.