Agaricus candidolutescens Linda J. Chen & R.L. Zhao
Index Fungorum number: IF 570195, Mycobank: 570195, Facesoffungi number: FoF01170
Pileus 27–42 mm diam., 2 mm broad at disc, convex to applanate; surface dry, smooth, silky, with woolly-fibrillose squamules towards the margin, pure white; margin appendiculate. Lamellae free, crowded, ventricose, intercalated with lamellulae, with more than 5 series, 2.5–4 mm broad, at first pink, then pinkish brown, later dark brown and finally almost black. Stipe 40–55 × 3–8 (10–12 at base) mm, cylindrical with a bulbous base, narrowly hollow, white, staining yellow when bruised, smooth above the ring, fibrillose below the ring. Annulus membranous, simple, white, fragile, upper side smooth, lower side fibrillose. Context firm, at first white on cutting, both in pileus and stipe, and quickly turning yellow at the stipe base, finally after 15 min uniformly brown. Odour of almonds. Macrochemical reactions: KOH reaction positive yellow, Schäffer’s reaction negative. Basidiospores 6.4–7.3 (−7.5) × 3.9–4.5 μm, [x = 6.8 ± 0.32 × 4.2 ± 0.2, Q = 1.49–1.77, Qm = 1.6 ± 0.05, n = 20], ellipsoid, smooth, dark brown, thick-walled, without germ pore. Basidia11–13 × 6.5–8 μm, clavate, hyaline, smooth, 4-spored. Cheilocystidia 18–38 × 7.5–13 μm, rare, simple, pyriform or sphaeropedunculate, hyaline, smooth. Pleurocystidia absent. Pileipellis a cutis composed of hyphae 5–9 μm in diam., cylindrical, hyaline, smooth, at times slightly constricted at the septa. (Figs. 1–2)
Etymology: “candido” refers to the white surface of basidiome; “lutescens” refers to slightly yellow of context on cutting.
Holotype: THAILAND, Chiang Rai Prov., Doi Pui, 25 July 2012, collector Jie Chen, LD2012129 (MFLU12-0962, holotype; HMAS373994, isotype).
Habitat: in groups, in rich soil of tree stump.
Specimens examined: THAILAND, Chiang Rai Prov., Doi Pui, 25 July 2012, collector Jie Chen, LD2012129 (MFLU12-0962, holotype; HMAS373994, isotype).