Phlegmacium violaceorubens (Moënne-Locc. & Reumaux) Niskanen & Liimat., Fungal Divers. 112: 155, 2022 Figs. 2G, 3G 1–G 4.

≡ Cortinarius violaceorubens Moënne-Locc. & Reumaux [as ‘ violaceo-rubens ’], Atlas des Cortinaires, Pars II (Annecy): 27, 1990

MycoBank: MB 559092

Description:— Pileus 4 cm, hemispherical to convex, first viscid but soon dry, coarsely innately fibrillose, deep violaceous brown. Lamellae adnate, 3–5 mm broad, crowded (L = 100–120, l = 1–2), deep blue. Stipe 6 cm long, 2 cm thick at apex, 3.5 cm wide at the base, bulbous with a rounded bulb, pale blue to violaceous brown, ornamented with violaceous brown fibrils; basal mycelium pale blue. Context pale blue in pileus, blue with a brownish tint at stipe apex, whitish with a pinkish tint on exposure at stipe base.

Basidiospores [20/1/1] 8–10 × 6–6.5 μm, av. 8.68 × 6.12 μm, Q = (1.23–)1.32–1.53(–1.67), Qav. = 1.42, ellipsoid, strongly verrucose. Basidia (35–)40–50(–54) × 8–10 μm, 4-spored, clavate, mostly colorless, hyaline. Cystidia absent. Lamellar trama hyphae 3–5 μm wide, mostly colorless, smooth. Stipe hyphae 4–8(–9) μm wide, colorless to ochraceous yellow, smooth. Pileipellis duplex, the upper layer (80–110 μm thick) gelatinous, composed of narrow, yellow to ochraceous yellow, smooth, thin-walled, long-celled hyphae measuring 1.5–2(–3) μm wide; lower layer composed of interwoven to parallel cylindrical, brownish yellow to yellow, thin-walled hyphae measuring 5–10(–13) μm wide. Clamp connections common in all parts of basidioma.

Habitat and distribution:—Solitary to scattered on soil in forests dominated by Picea . Autumn. Currently known from France, Germany, Sweden, Finland (Liimatainen et al. 2014), and northwestern China (this study).

Specimen examined:— CHINA. Xinjiang Uygur Autonomous Region: Ili Kazakh Autonomous Prefecture, Zhaosu County, in a forest with Picea, altitude 2237 m, 5 August 2021, Liu-Kun Jia 1929 (KUN-HKAS124254)

Notes:— Phlegmacium violaceorubens is mainly characterized by its slightly viscid violaceous brown pileus with abundant fibrils, deep blue lamellae, rounded bulb and ellipsoid basidiospores measuring 8–10 × 6–6.5 μm. This species grows in Picea -dominated forests.

Phlegmacium violaceorubens is close to P. cyanites (Fr.) M.M. Moser (1960: 337) and P. boreicyanites (Kytöv., Liimat., Niskanen & A.F.S. Taylor) Niskanen & Liimat. (2022: 141) . However, P. cyanites is separated by its larger basidioma, greyish blue to greyish brown pileus, and narrower basidiospores (8.8–10.9 × 5.2–6.3 μm, Q = 1.59–1.84, Qav. = 1.66–1.77). In addition, P. cyanites grows in mixed forests of coniferous and deciduous trees (Liimatainen et al. 2014). Phlegmacium boreicyanites has a pale greyish brown pileus, more abundant universal veil-forming girdles on the stipe, and narrower basidiospores (9.1–10.4 × 5.4–6.3 μm, Q = 1.58–1.80, Qav. = 1.66–1.73). It grows in boreal mixed forests of Picea, Betula, and Populus (Liimatainen et al. 2014) .