Cortinarius perrotensis A. Paul

Cortinarius perrotensis A. Paul et al., Mycol. Progr. 20: 1429. 2021. Figs 3F, 6K, 7K. Pileus 16–32 mm diam., convex when young, later plane, margin inrolled at first; surface innately fibrillose, somewhat viscid when moist, soon drying with shiny; greyish brown, paler at the margin. Lamellae emarginate, moderately crowded, violet at first, soon greyish violet to pale brown, edges slightly serrate. Stipe 32–69 mm long, 5–8 mm thick above, clavate, thickened at the base (9–15 mm); surface fibrillose, whitish, blue tinge at the apex when young, basal mycelium whitish. Universal veil white, soon yellowish, sometimes forming a sock like sheath on the stipe. Context fleshy, whitish, at first bluish in the stipe apex. Odour indistinct. Taste mild. Basidiospores 6.8–8.4 × 5.4–6.1 μm, Q = 1.17– 1.41, Xav. = 7.6 × 5.8 μm, Qav. = 1.31, subglobose, broadly ellipsoid to ellipsoid, moderately verrucose. Basidia clavate, 4-spored, hyaline to subhyaline, rarely light olivaceous brown to olivaceous brown. Lamellar edge fertile. Pileipellis duplex: epicutis of hyaline, light olivaceous brown to olivaceous brown hyphae; hyphae 3–10 μm wide, smooth to weakly encrusted spots; hypocutis well developed, hyphae 8–23 μm wide, hyaline to olivaceous brown, irregular, smooth. Clamp connections present. Ecology and distribution: Gregarious in broadleaf-conifer forests of Betula and Larix. Known only from Heilongjiang Province in China. It was described from Eastern North America in broadleaf-conifer forests. Specimen examined: China, Heilongjiang Province, Tahe County, Talin Forest Farm, in mixed forest of L. gmelinii and B. platyphylla, 28 Aug. 2016, M.L. Xie, HMJAU 48662. Notes: Cortinarius perrotensis is a new record in China. It is a small-sized species. The pileus is usually greyish brown without a bluish tinge, the violet lamellae soon become pale brown and are slightly serrate at the edge. The basidiospores in Chinese materials, which average 7.6 × 5.8 μm, are slightly narrower than those of North American specimens. In phylogenetic analyses, the Chinese specimens formed a well-supported monophyletic clade with the holotype.