Cortinarius azureovelatus P. D. Orton, Naturalist

Cortinarius azureovelatus P.D. Orton, Naturalist, Leeds (Suppl.): 147. 1958. Figs 2C, 6C, 7C. Pileus 50–110 mm diam., hemispherical at first, later convex to plane, somewhat wavy at the margin, surface viscid to somewhat glutinous when moist, somewhat shiny to distinctly glittery when dry, not hygrophanous, innately fibrillose, sometimes wrinkled when mature, at first pale to yellowish, then brownish yellow,paler at the margin. Lamellae emarginate at first, then adnate, moderately crowded, violet when young, later greyish brown to rusty brown, edges almost even. Stipe 55–120 mm long, 12–23 mm thick, cylindrical to subcylindical, slightly thickened at the base, surface with white fibrillose, later becoming yellowish, bluish tinge at the stipe apex, basal mycelium whitish. Universal veil yellowish, forming a sock like sheath on the stipe. Context fleshy, thick, strong bluish violet when young, especially at the stipe apex, later white to yellowish, sometimes somewhat hollow in the stipe when mature. Odour indistinct or somewhat raphanoid. Taste mild. Basidiospores 7.4–9.7 × 6.3–7.7 μm, Q = 1.06–1.34, Xav. = 7.9–9.0 × 6.8–7.0 μm, Qav. = 1.15–1.27, subgloboid to broadly ellipsoid, rarely ellipsoid, rather weakly to moderately verrucose. Basidia clavate, 4-spored, hyaline to subhyaline, rarely yellowish to yellowish brown. Lamellar edge fertile. Pileipellis duplex: epicutis well developed, hyphae upward loosely entangled, hyaline or yellowish to yellowish brown, 3–7 μm wide, smooth; hypocutis well developed, hyphae 9–25 μm wide, hyaline or slightly yellowish brown, cylindrical, smooth. Clamp connections present. Ecology and distribution: Solitary or gregarious under Betula and/or Quercus. Known from Northeast China. Widespread in Europe and Siberia of Russia as well. Specimens examined: China, Heilongjiang Province, Heihe City,ShengshanNationalNatureReserve,in Betulaplatyphylla forest, alt. 300 m, 20 Aug. 2017, G.H. Cheng, HMJAU 48654, HMJAU 48655, HMJAU 48713; Inner Mongolia Autonomous Region, Arxan County, in Betula platyphylla forest, alt. 1200 m, 22 Aug. 2018, M.L. Xie, HMJAU 48656; Jilin Province, Antu County, Changbai Mountain National Nature Reserve, in Quercus mongolica dominated forest with Betula platyphylla and Aceraceae, alt. 770 m, 20 Sep. 2020, M.L. Xie, HMJAU 48734, HMJAU 48735, HMJAU 48736, HMJAU 48737; Yanji County, Sandaowan town, Wupiyegou, in Quercus mongolica forest, alt. 580 m, 7 Sep. 2018, M.L. Xie, HMJAU 48657; Jiaohe County, Haiqing Forest Farm, in broadleaf forest of Betula platyphylla and Aceraceae, alt. 360 m, 13 Sep. 2018, M.L. Xie, HMJAU 48658. Notes: Cortinarius azureovelatus is a newly recorded species in China. It is characterized by its robust, ochraceous basidiomata, and viscid to somewhat glutinous pileus. Bluish tinges are only present on the lamellae and stipe apex of young specimens. This species usually occurs in broadleaf forests, associated with Betula and Quercus. The sister species of C. azureovelatus is C. albidipes from which it differs by six substitutions and indel positions in nrITS region, with a similarity of 99.0 %.