Cortinarius subclackamasensis Q. Y. Zhang

Cortinarius subclackamasensis Q.Y. Zhang et al., Front. Cell. Infect. Microbiol. 13: 11. 2023. Figs 5A, B, 6Q, 7Q. Pileus 50–135 mm diam., hemispherical when young, later plane to convex, margin ± wavy finally, surface weakly hygrophanous when moist, especially at margin, violet grey to dull violet grey when young, finally brownish grey to brownish orange, sometimes reddish brown at the centre, brownish orange with violet at margin. Lamellae emarginate, moderately crowded, greyish violet when young, then pale orange to brown, edges paler, weakly serrate. Stipe 65–78 mm long, 12–15 mm thick, subcylindrical when young, later cylindrical, surface whitish fibrillose, bluish tinges at the apex. Universal veil yellowish, forming fibrils on pileus and sock like sheath on the stipe, later sparse. Context in pileus fleshy, soft, sometimes hollow in the stipe, marbled watery when moist, at first violet in pileus and in stipe, later whitish with bluish tinges, especially at the stipe apex, yellowish brown at base. Odour radish. Taste mild. Basidiospores (8.0–)8.6– 10.1(–10.8) × 5.1–6.7 μm, Q = 1.42–1.77, Xav. = 9.1–9.5 × 5.8–6.2 μm, Qav. = 1.54–1.61, ellipsoid, moderately and densely verrucose, moderately dextrinoid. Basidia clavate, 4-spored, hyaline to subhyaline, rarely yellowish to yellowish brown. Lamellar edge fertile. Pileipellis duplex: epicutis well developed, hyphae parallel, yellowish to yellowish brown, 3–10 μm wide, smooth; hypocutis well developed, hyphae 11–29 μm wide, hyaline to slightly yellowish brown. Clamp connections present. Ecology and distribution: Scattered under broadleaf trees of Betula, Populus, and Salix or mixed forests. Known from Beijing, Hebei, Inner Mongolia, Jilin, Qinghai and Sichuan of China. Specimens examined: China, Beijing Municipality, Huairou District, Yanqihu Town, 19 Sep. 2003, H. Deng & L. Jiao, HMAS 86629; Mentougou District, Xiaolongmen National Forest Park, in Populus forest, alt. 1156–1201 m, 4 Sep. 2020, K. Wang, HMAS 291450, HMAS 291452; Hebei Province, Laiyuan County, Prairie Air, in shrubs, alt. 1748 m, 24 Aug. 2020, X.J. Xie, HMAS 291480; Pingshan County, Tuoliang National Nature Reserve, in Betula forest, 31 July 2020, G.J. Li, HBAU 15319; in Betula forest, alt. 1450–1684 m, 20 Aug. 2020, G.J. Li, HBAU 15471, HBAU 15473, Y.B. Guo, HMAS 281435, X. Zhang, HMAS 249875, HMAS 291498, HMAS 291503, T.T. Fan, HMAS 291375; in mixed forest of Betula, Quercus and Pinus, alt. 1470 m, 20 Aug. 2020, T.K. Zong, HMAS 291504; in Betula forest, alt. 1542 m, 22 Aug. 2020, G.J. Li, HBAU 15552, X. Zhang, HMAS 249872; in Larix forest, alt. 2031 m, 22 Aug. 2020, T.T. Fan, HMAS 281433, X.J. Xie, HMAS 291477; in Larix forest, alt. 1560–1585 m, 22 Aug. 2020, Y.B. Guo, HMAS 281437, HMAS 291524; Yu County, Jinhekou Forest Park, in broadleaf forest, 8 Aug. 2020, G.J. Li, HBAU 15437, HBAU 15457; ibid., 27 Aug. 2020, G.J. Li, HBAU 15665, HBAU 15672, HBAU 15679; Yu County, Xiao Wutai Mountain National Nature Reserve, under Populus and Acer, alt. 1356–1468 m, 8 Aug 2020, Y.B. Guo, HMAS 291387, X.M. Jiao, HMAS 291423, HMAS 291424, L. Sun, HMAS 291430, HMAS 291431; under Populus and Acer, alt. 1319–1482 m, 27 Aug. 2020, T.T. Fan, HMAS 281445, HMAS 291381, Y.B. Guo, HMAS 291399, HMAS 291400, X.N. Shan, HMAS 291362, HMAS 291363, HMAS 291365, X.J. Xie, HMAS 281649, HMAS 281650, HMAS 291489, HMAS 291490, HMAS 291491, HMAS 291492, X. Zhang, HMAS 291500, HMAS 291502, T.K. Zong, HMAS 281652, HMAS 291518, HMAS 291528, HMAS 291529; Inner Mongolia Autonomous Region, Aohan Qi, Daheishan National Nature Reserve, 4 Sep. 2015, T.Z. Liu, J.N. Zhao & H.L. Meng, CFSZ 10743; Balinyou Qi, Saihanwula National Nature Reserve, 1 Sep. 2017, T.Z. Liu & Wulantuya, CFSZ 18827; Genhe County, Mangui Town, under Populus trees, alt. 603 m, 24 Aug. 2017, M.L. Xie, HMJAU 48642; Jilin Province, Antu County, Changbai Mountain National Nature Reserve, in broadleaf forest of Populus and Salix, alt. 770 m, 20 Sep. 2020, M.L. Xie, HMJAU 48717, HMJAU 48718, HMJAU 48719; Qinghai Province, Huzhu County, Beishan Forest Farm, alt. 3000 m, 15 Aug. 2004, L.D. Guo & Y. Zhang, HMAS 145566; Sichuan Province, Batang County, roadside to Litang County, in mixed forest of Pinus densata, Abies and Rosaceae, alt. 3711 m, T.Z. Wei, L.H. Sun, Z.X. Wu & R.C. Zhang, HMAS 277064; Zhejiang Province, Qingyuan County, Baishanzu National Park, in evergreen broadleaf forest of Lithocarpus scattered Rhododendron and Theaceae, 12 Sep. 2013, J.L. Chen, HMJAU 48768; ibid., 5 Sep. 2020, J.L. Chen, HMJAU 48749, HMJAU 48750, HMJAU 48757. Notes: Cortinarius subclackamasensis is characterized by ellipsoid basidiospores. It produces medium- to large-sized basidiomata, a violet grey to brownish orange or reddish brown pileus, a yellowish universal veil, and ellipsoid basidiospores, on average 9.1–9.5 × 5.8–6.2 μm. It is a widely distributed species in China, and can be easily distinguished from other species in sect. Anomali. Two specimens, HBAU 15665 (MW862366) and HBAU 15437 (MW862347), were reported as C. caninus and C. xanthocephalus respectively by Shi et al. (2022). However, the morphological and phylogenetic investigations concluded that they were C. subclackamasensis. Phylogenetically, the sister species of C. subclackamasensis is Cortinarius sp7 from which it differs by seven substitutions and indel positions in the nrITS region, with a similarity of 98.8 %. In molecular data, the intraspecific genetic variability of C. subclackamasensis is 0.8 % in the nrITS region.