Stropharia microaeruginosa J. Z. Xu 2024, sp. nov.

Stropharia microaeruginosa J. Z. Xu sp. nov. Fig. 4 Diagnosis. Stropharia microaeruginosa pileus bluish-grey when young becoming lighter toward margins, later greyish-turquoise lightening towards the edges and surface radially striate when young, lamellae adnate to subdecurrent, stipe with white squamules at the base, acanthocytes absent making it unique amongst the Stropharia species. Holotype. China, Fujian Province, Sanming City, Tianbaoyan Nature Reserve, Shangping Village, scattered in the moss under mixed forests dominated by phyllostachys pubescens and coniferous forest, alt. 1100 m, 31 October 2023, J. P. Liao (HMJU 12635, holotype). Etymology. “ micro ” means “ small ”, referring to the small basidiocarps and the margins often with partial veil remnants. Description. Pileus 27–38 mm diam., centre of pileus bluish-grey (20 F 3) when young becoming lighter towards margins, later greyish-turquoise (24 D 4) lightens toward the edges, initial convex, the edge of the pileus upturned at maturity, smooth surface, viscid to glutinous, the margins often with partial veil remnants, submembranous, surface radially striate when young, gradually becomes less obvious as it matures. Lamellae adnate to subdecurrent, moderately crowded, grey (15 C 1), with lamellulae in 1–3 tiers. Stipe 51–75 mm long and 3.7–6.0 mm wide, concolorous with the pileus and lightening upwards, white squamules at the base, sometimes evanescent annulus in the upper part of the stipe. Further, slightly broad and with whitish rhizoids at the base. Basidiospores [30 / 4 / 3] (5.4) 6.2–7.3 – 8.2 (8.8) × (3.7) 4.0–4.3 – 4.9 (5.0) µm, Q = (1.10) 1.42–1.99 (2.06), Qm = 1.69, elliptical, with an obvious germ-pore, light brown in KOH. Contains 1–2 guttulates. Basidia (16.4) 17.9–21.0 – 23.9 (27.0) × (5.2) 5.9–7.3 – 9.0 (9.9) µm, 2–4 spored, clavate, sterigmata up to 3.4 µm long, hyaline in KOH. Pleurocystidia (27.6) 33.5–39.9 – 46.3 (47.4) × (10.2) 11.1–13.6 – 16.0 (16.3) μm, clavate, with or without short mucronate apex, with an amorphous highly refractive content distributed in enlarged or raised areas. Cheilocystidia (29.8) 30.7–36.1 – 41.4 (45.6) × (7.9) 8.4–11.6 – 14.4 (16.1) μm. clavate, with homogenous content, mucronate at the apex, expanded apically, tapering downwards, sometimes curved. Chrysocystidia rare. Lamellae trama regular, subparallel, 6.7–14.3 µm wide, hyaline in KOH. Pileipellis a cutis of subparallel, slightly upturned, hyphae 2.7–5.5 µm wide. Clamp connections are present. Habitat. Scattered in the moss under mixed forests dominated by phyllostachys pubescens and coniferous forest Known distribution. Known only from south-eastern China. Additional material examined. Fujian Province, Sanming City, Tianbaoyan Nature Reserve, Shangping Village, scattered in the moss under mixed forests dominated by phyllostachys pubescens and coniferous forest, alt. 1100 m, 31 October 2023, J. P. Liao (HMJU 12422). Comments. This species is characterised mainly by the centre of pileus bluish-grey when young becoming lighter toward margins, later greyish-turquoise lightening towards the edges, the margins often with partial veil remnants, surface radially striate, stipe concolorous with the pileus and white squamules at the base, the spores with an obvious germ pore and chrysocystidia rare.