Agaricus brunneopileatus Callac & R.L. Zhao
Index Fungorum number: IF 570217; Facesoffungi number: FoF 01210
Pileus 60–80 mm in diam., 5 mm thick at disc, parabolic when young, then convex; surface dry, completely covered by fibrils and broken into appressed squamules, triangular, dense and darker at the disc, dark brown (oac639), reddish brown discolouring on touching, margin decurved. Lamellae free, crowded, intercalated with lamellulae, 5 mmbroad, firstly white, then pink, finally brown dark brown. Stipe 110–150 ×7–8 (apex) – 10–15 (base) mm, cylindrical and bulbous at base, hollow, surface smooth and white above the annulus, heavily fibrillose, brown below the annulus, not staining on touching. Annulus membranous, pendant, simple, superous, up to 16mm broad, upper side smooth and white, lower side heavily fibrillose to smooth when mature, with brown tone. Context fleshy, on cutting white, and no discolouration on exposure. Odour similar to that of Lepiota cristata. Macrochemical reaction: KOH and Schäffer’s reactions negative. (Fig. 2)
Basidiospores 4.9–5.8 × 2.5–3.6 μm [x = 5.4 ± 0.3× 3.2 ± 0.2, Q= 1.6–1.9, Qm = 1.7 ± 0.1, n = 20], ellipsoid, reddish brown, smooth, thick-walled, without germ pore. Basidia 12.6–18 × 6.2–8.8 μm, clavate, smooth, hyaline, 4-spored. Cheilocystidia 12–24 × 7–13 μm, pyriform, ellipsoid, occasionally 1–2 septate at the base, hyaline, smooth. Pleurocystidia absent. Pileipellis a cutis comprising hyphae 3.2–6.6 μm in diam., long cylindrical, with brown pigments, smooth, slightly constricted at the septa. Annulus hyphae of elements 3–8.6 μm in diam, cylindrical, hyaline, smooth. (Fig. 3)
Habitat: solitary in forest.
Material examined: CHINA, Yunnan Prov., Cangyuan county, Mengjiao, Nuozhang Village, 6 July 2012, collected by O. Raspé and R.L. Zhao, ZRL2012115 (HMAS274001, holotype). China, Yunnan Prov., Dali, Yangbi County, Sangbuliao Village, 28 July 2014, collected by H.Y Su, ZRL2014144 (HMAS253915).
Fig. 1 Phylogeny of Agaricus subgenus Spissicaules generated from Bayesian analysis of ITS sequences, rooted with A. campestris. Bootstrap support (BS) values > 50 % and Bayesian posterior probability (PP) values > 80 % (or >50% in some main clades) are given at the internodes (PP/BS). BT^ means the sequence is from type specimen; a clade with thick branch is corresponding a certain section in Fig. 1