Agaricus erectosquamosus

Pileus 40–50 mm in diam., 5 mm thick at the disc, convex to plane; surface dry, whole capcovered by squamules, erect, dense at the disc, brown against a dirty white background; margin decurved and exceeding. Lamellae free, 5 mm broad, ventricose, crowded, intercalated with lamellulae, reddish brown, brown to dark brown with age. Stipe 45 × 5 mm, cylindrical to slightly clavate upon maturing, hollow, smooth and white above the annulus, and squamose, white to light brown below the annulus, with indistinctive staining on touching. Annulus membranous, double, large, entire, pendant or subperonate, upper surface smooth, white and lower surface heavy floccose, and often cogwheel-like, white and light brown at the margin. Context fleshy, on cutting pale white both in pileus and stipe, and without discolouration on exposure. Odour indistinct or slightly phenol. Macrochemical reactions: KOH reaction orange, Schäffer’s reaction negative. Basidiospores (6.6–) 6.9 –7.6 × 4.1–4.6 (−5) μm, [x = 7.2 ± 0.31 × 4.4 ± 0.2, Q = 1.51–1.73, Qm = 1.63 ± 0.05, n = 20], ellipsoid to oblong, smooth, brown, thick-walled, without a germ pore. Basidia 15–22 × 6.5–7.5 μm, clavate to broadly clavate, hyaline, smooth,4-(2-) spored. Cheilocystidia 18– 30 × 9–16.5 μm, abundant, simple, or occasionally in short chains, globose to pyriform or sphaeropedunculate, rarely clavate, hyaline, smooth. Pleurocystidia absent. Pileipellis a cutis composed of hyphae 4–12.5 μm in diam., shortly cylindrical, with brownish membranous pigments, smooth, distinctively constricted at the septa. Annulus composed of hyphae 7 10 μm in diam., which are hyaline and smooth. (Figs. 1 a-b –2)

Index Fungorum number: IF 570199, Mycobank: MB 570199, Facesoffungi number: FoF 01181

Etymology: the epithet “erectosquamosus” refers to the squamose pileus covered by upturned squames.

 Holotype: THAILAND, Chiang Mai Prov., Chiang Mai Zoo, 4 August 2012, collector Jie Chen, LD2012165 (MFLU12- 0993, holotype; HMAS273992, isotype).        

Habitat: scattered in soil of grasslands.

Specimens examined: THAILAND, Chiang Mai Prov., Chiang Mai Zoo, 4 August 2012, collector Jie Chen, LD2012165 (MFLU12- 0993, holotype; HMAS273992, isotype).