Cortinarius lepidopus Cooke

Cortinarius lepidopus Cooke, Grevillea 16 (no. 78): 43. 1887. Figs 3A, 6H, 7H. Pileus 33–72 mm diam., hemispherical when young, later plane to convex with rounded umbo, surface weakly hygrophanous when moist, at first white fibrillose, especially at the margin, sometimes slightly wrinkled, dull yellowish brown with somewhat reddish, margin paler. Lamellae adnexed to emarginate, moderately crowded, violet when young, then greyish blue to yellowish brown, edges uneven. Stipe 65– 78 mm long, cylindrical at above, 12–15 mm thick, clavate at base, 10–21 mm, white fibrillose, bluish tinges at apex, basal mycelium whitish. Universal veil white, forming a white sock like sheath on the stipe, then discolouring yellowish, sometimes forming a ring at the middle of the stipe. Context in pileus rather thin, white, in stipe bluish tinges, especially at apex. Odour indistinct. Basidiospores 6.3–8.4(–9.0) × 5.1– 6.9 μm, Q = 1.10–1.39, Xav. = 7.2–7.6 × 5.9–6.1 μm, Qav. = 1.18–1.27, subgloboid to broadly ellipsoid, rather weakly to moderately verrucose. Basidia clavate, 4-spored, hyaline to yellowish brown. Lamellar edge fertile. Pileipellis duplex: epicutis thinly developed, hyphae parallel, hyaline to yellowish brown, 4–12 μm wide, smooth; hypocutis well developed, hyphae 15–34 μm wide, hyaline to slightly yellowish brown, smooth. Clamp connections present. Ecology and distribution: Known from Northeast China under Betula platyphylla, or mixed with Larix gmelinii, and from Xizang under mixed forests dominated by Abies georgei var. smithii. It also known from Europe and Western Siberia in coniferous forests. Specimens examined: China, Heilongjaing Province, Mohe County, Qianshao Forest Farm, in mixed forest of Larix gmelinii and Betula platyphylla, alt. 540 m, 20 Aug. 2017, M.L. Xie, HMJAU 48634, HMJAU 48635, HMJAU 48636; in Betula platyphylla forest, alt. 540 m, 25 Aug. 2016, M.L. Xie, HMJAU 48641; Gulian Forest Farm, in Betula platyphylla forest, alt. 550 m, 25 Aug. 2016, M.L. Xie, HMJAU 48640; Inner Mongolia Autonomous Region, Genhe County, ManGui Town, in mixed forest of Larix gmelinii and Betula platyphylla, alt. 630 m, 24 Aug. 2017, M.L. Xie, HMJAU 48638, HMJAU 48639; 10 Sep. 2019, M.L. Xie, HMJAU 48715; Xizang Autonomous Region, Linzhi City, Lulang Town, Sejila Mountain, in Abies dominated forest with Rhododendron, alt. 3340 m, 7 Sep. 2014, T.Z. Wei, J.Y. Zhuang, X.Y. Liu & H. Huang, HMAS 271923, HMAS 271997, HMAS 272035, HMAS 273324; in Abies dominated forest with scattered Quercus aquifolioides, Rhododendron and Rosa, alt. 3451 m, 22 Sep. 2015, T.Z. Wei & B.B. Li, HMAS 275384, HMAS 275397; Linzhi City, Sejila Mountain, in Abies georgei var. smithii dominated forest with Rhododendron, Sep. 2014, S.R. Wang, HMJAU 48744. Notes: Cortinarius lepidopus is a newly recorded species in China. It is characterized by the greyish brown to reddish brown pileus without bluish tinges and the yellowish universal veil. The Chinese specimens are distributed in two floras, northeast China and the Tibetan Plateau, in which the nrITS sequences from the specimens of northeast China are identical to European sequences, while the nrITS sequences from the specimens of the Tibetan Plateau usually differ from others by three to four substitutions and indel positions. The Tibetan specimens are almost indistinguishable from other specimens in morphology, except that they have three to four substitutions and indel positions, as well as a special plateau ecology, so they were treated as C. lepidopus. The taxonomy of this species in China requires further research. Phylogenetically, C. lepidopus and C. modestus are paraphyletic, but the sequences of C. lepidopus consistently differ from those of the latter by at least two nucleotides in the nrITS region, and here we treat them as different species following Dima et al. (2021).