Cortinarius caninus Fr., Epicr.

Cortinarius caninus (Fr.) Fr., Epicr. syst. mycol. (Upsaliae): 285. 1838. [1836–1838]. Figs 2F, 6E, 7E. Pileus 46–87 mm diam., hemispherical when young, then plane to convex, margin incurved, surface not viscid, not hygrophanous, innately fibrillose, greyish brown with bluish at first, then ochrace brown to yellowish brown, paler at the margin, dull. Lamellae emarginate, moderately crowded, greyish blue at first, soon greyish orange to brown, edges almost even. Stipe 60–100 mm long, 8–13 mm thick above, cylindrical, slightly thickened at the base, surface whitish fibrillose, bluish tinges at the upper part, basal mycelium whitish. Universal veil white, soon yellowish, usually forming a thin, incomplete band on the stipe. Context thick, firm at first, white, with bluish tinges at the stipe apex, later becoming yellowish, becoming hollow in the stipe. Odour indistinct. Basidiospores 7.1–9.7 × 5.8–7.7 μm, Q = 1.13–1.55, Xav. = 8.4–8.8 × 6.5–6.8 μm, Qav. = 1.23–1.37, subgloboid, broadly ellipsoid to ellipsoid, moderately verrucose. Basidia clavate, 4-spored, hyaline to subhyaline, rarely yellowish to yellowish brown. Lamellar edge fertile. Pileipellis duplex: epicutis thinly to moderately developed, hyphae interwoven, hyaline or yellowish to yellowish brown hyphae, 3–8 μm wide, smooth to slightly encrusted; hypocutis well developed, hyphae 10–20 μm wide, hyaline or slightly yellowish brown. Clamp connections present. Ecology and distribution: Sparse to gregarious in Larix gmelinii forests or mixed forests with Betula platyphylla, sometimes in broadleaf forests of Betula and Populus. Known from Heilongjiang, Inner Mongolia, Sichuan, and Xinjiang of China. Widespread in Europe and North America as well under coniferous forests. Specimens examined: China, Heilongjiang Province, Mohe County, Qianshao Forest Farm, in Larix gmelinii forest, alt. 510 m, 26 Aug. 2016, M.L. Xie, HMJAU 44258; Tahe County, Taergen Forest Farm, in Larix gmelinii forest, 21 Aug. 2017, M.L. Xie, Y. Wang & Z.H. Luo, HMJAU 44367, HMJAU 44371, HMJAU 44372, HMJAU 44373; Talin Forest Farm, in Larix gmelinii forest, alt. 400 m, 28 Aug. 2016, M.L. Xie, HMJAU 44279; Inner Mongolia Autonomous Region, Genhe County, Jinhe Town, in Larix gmelinii forest, alt. 750 m, 25 Aug. 2018, M.L. Xie, HMJAU 44497; Mangui Town, in mixed forest of Larix gmelinii and Betula platyphylla, alt 640 m, 10 Sep. 2019, M.L. Xie, HMJAU 48714; Sichuan Province, Seertar County, alt. 3092 m, 11 Aug. 2013, W.L. Lu, HMAS 268204; Xinjiang Uygur Autonomous Region, Zhaosu County, in broadleaf forest of Betula and Populus, alt. 2244 m, 31 July 2021, Y. Wang, HMJAU 49114, HMJAU 49115. Notes: Cortinarius caninus is a newly recorded species in China. It is characterized by robust basidiomata and an ochraceous brown and dry pileus. In China, it is usually associated with Larix gmelinii, as well as some broadleaf trees like Betula and Populus. The bluish tinges are only present in the pileus, lamellae, and stipe apex when young. Basidiospores are somewhat narrower than European and North American specimens (Dima et al. 2016, 2021). The newly generated Chinese nrITS sequences and the neotype sequence KX302206 have two to five substitutions and indel positions, with a similarity of 99.2–99.7 %, here we recognize the Chinese specimens as C. caninus.