Cortinarius subtropicus

Cortinarius subtropicus P. Long & Z.H. Chen,

MycoBank Number: 850394

Basidiomes small, development type stipiocarpic. Pileus 2.1– 4.6 cm, at first broadly convex, then lower convex to plane, broadly umbonate at the centre, margin incurved; at first violaceous (15A4–15B7), tinged brown (6A5–6C7) at the centre then becoming orange brown (5B2–5B6), brown (5A4–5B6) universal veil remains at margin; surface smooth when dry or glutinous when wet, pileipellis is easy to separate. Context thin, creamy white, soft, beige (3A1–A2) when bruised. Lamellae adnate, bluish violet (18A2–18B2) with pale greyish (18B1) to brownish (5A4–5B7), rust brown (5C7) when dry, moderately distant. Stipe cylindrical to weakly clavate, bend, gradually slender to the apex, 6.4–7.2 cm long, 0.5–1.0 cm wide, lilac (15A2–15B2) when young, dirty white at maturity, leaving an ochraceous (5D7) to orange (5B6) ring on the upper stem, hollow in centre, crumbly. Odour indistinct. Basidiospores [120/6/6] (6.6–) 7.0–9.1 (–10.3) × (5.9–)6.1–7.9 (– 10.3) μm, av. 7.8 × 6.4 μm, Q = 1.10–1.38 (1.41), Qm = 1.24 ± 0.01, subglobose to ellipsoid, yellowish brown, moderately verrucose, without amyloid and dextrinoid reaction. Basidia 32–48 × 9–12 μm, 4-spored, sterigmata 2.8–4.9 μm, clavate to subcylindrical, colourless or with amber yellow oily inclusions. Pileipellis duplex, hyphae 4–8 μm wide, epicutis gelatinous, 30–40 μm thick, composed of colourless or amber yellow, irregularly arranged and moderately interwoven hyphae, hypocuits 130–200 μm thick, composed of colourless or amber yellow, nearly parallel cylindrical hyphae. Lamellar edges fertile. Cystidia absent. Lamellar trama regular, 40–80 μm thick, composed of parallel arranged hyphae, hyphae 3–6 μm wide. Stipitipellis gelatinous, stipe hyphae 3–6 μm wide, thinwalled, cylindrical, subparallel arranged. Clamp connections present in all tissues of the basidiome. Habitat, ecology and distribution. Solitary to gregarious on soil in under evergreen broad-leaved forest, on the ground, known from Hunan, China; July.

Additional specimens examined. China, Hunan Province: Sangzhi County, Badagongshan National Nature Reserve, at 29.683144°N, 109.754104°E, alt. 1645 m, 27 July 2020, Z.H. Chen, P. Long and S.N. Li, (MHHNU 31954). China, Hunan Province: Sangzhi County, Badagongshan National Nature Reserve, at 29.6767°N, 109.750696°E, alt. 1625 m, 28 July 2020, Z.H. Chen, P. Long and S.N. Li, (MHHNU 31964). China, Hunan Province: Sangzhi County, Badagongshan National Nature Reserve, at 29.676642°N, 109.750674°E, alt. 1625 m, 28 July 2020, Z.H. Chen, P. Long and S.N. Li, (MHHNU 31981). China, Guangxi Province: Xingan County, Maoershan National Nature Reserve, alt. 1900 m, 24 July 2012, X.B. Liu, (KUN-HKAS 75760).

Notes. Cortinarius subtropicus has an epicutis pileipellis that can be easily separated from the context of the pileus. Besides, pileus become brown without lilac or dark olive tint at maturity comparing with other members of section Delibuti.

Fig 1. Phylogenetic tree of Cortinarius sect. Delibuti inferred from a combined matrix of ITS and LSU through maximum likelihood and Bayesian inference. Bayesian posterior probabilities (PP) > 0.90 and bootstrap values (BP) >85% are reported at the nodes (PP/BP); “–” indicates that the support value was less than the respective threshold. The three newly described species are highlighted in bold. Aus: Australia; EA: East Asia; Eur: Europe; NAm: North America; NZ: New Zealand.