Agaricus variabilicolor

Pileus 35–80 mm in diam, 4–7 mm thick at the disc, pulvinate, hemisphaerical when young, then expanding convex, top applanate or slightly depressed; covered by fibrillose scales or complete scales, colour variable, mostly brown, but also with light brown scales in some cases, appressed or slightly recurved; margin decurved and often appendiculate. Lamellae free, crowded, intercalated with lamellulae, 4–8 mm broad, at first pink, then reddish brown, brown, finally dark brown. Stipe 50–100 × 7–10 mm, equal to slightly tapering towards the base; narrow hollow or stuffed; white; smooth above the annulus, and scabby or scurfy below the annulus, not discolouring on touching. Annulus membranous, 6–12 mm in diam, pendant, simple, fragile and attached at the margin of pileus or entirely at the stipe, upper side smooth, white, and lower side floccose white or with brown colouration. Context firm, on cutting, at first white, both in pileus and stipe, then quickly turning slightly greyish pick in the pileus and slightly pink in stipe, finally after 15 min uniformly light brown. Odour pleasant. Macrochemical reactions: KOH reddish brown or not on surface of pileus, no colour change on stipe; Schäffer’s reaction negative. Basidiospores 4.1–5.9 × 2.4–3.9 μm [x = 5 ± 0.3 × 2.9 ± 0.3, Q = 1.3–2, Qm = 1.6 ± 0.2, n = 60], ellipsoid to elongate ellipsoid, light brown to brown, smooth, thick-walled, without germ pore. Basidia16–23 × 5.5–7.2 μm, clavate or cylindrical, hyaline, smooth, 4-spored. Cheilocystidia abundant, pyriform, broad clavate, 9–24 × 7–14 μm, smooth, hyaline. Pleurocystidia absent. Pileipellis a cutis composed of cells 4–23 × 2.5 μm, distinctly constricted at the septa, contains light brown, brown membranous pigments. Annulus composed of rectangular, ellipsoid, or subsphaerical cells, 3– 9 × 2.5 μm, hyaline, branched.

Index Fungorum number: IF 570200, Mycobank: MB 570200, Facesoffungi number: FoF01186

Etymology: epithet “variabilicolor” refers to the variable colour of the pileus.

Holotype: THAILAND, Chiang Mai Prov., Mae Taeng Dist., Ban Pha Deng village, N 19°17.123′ E 98°44. 009′, elev. 900 m, 10 May 2007, collected by Phongeun Sysouphanthong, ZRL4007 (BBH19637, holotype; HMAS, isotype).

Habitat: gregarious or scattered in forest.

Specimens examined: THAILAND, Chiang Mai Prov., Mae Taeng Dist., Ban Pha Deng village, N 19°17.123′ E 98°44. 009′, elev. 900 m, 10 May 2007, collected by Phongeun Sysouphanthong, ZRL4007 (BBH19637, holotype; HMAS, isotype). THAILAND, Chiang Mai Prov., Mae Taeng Dist., Ban Pha Deng village, N 19°17.123′ E 98°44. 009′, elev. 900 m, 10 May 2007, collected by Phongeun Sysouphanthong, ZRL4012 (BBH19242); same location, 8 May, collected by Phongeun Sysouphanthong, ZRL4002 (BBH19632).