Agaricus globocystidiatus Drewinski & M.A. Neves, Phytotaxa

Chen, Jie, Callac, Philippe, Llarena-Hernández, Régulo Carlos & Mata, Gerardo, 2019, Two species of Agaricus subg. Minoriopsis from Mexico, Phytotaxa 404 (3), pp. 91-101 : 96-100

Agaricus globocystidiatus Drewinski & M.A. Neves, Phytotaxa 314 (1): 68. 2017 . ( Figs. 4 , 5 )

Macroscopic description:—Pileus 9.5–15.5 cm diam., conical truncated to convex when young, then plano-convex, finally plane at maturity, covered with concentrically arranged, reddish-brown scales on beige background, densely at disc with an entirely dark reddish-brown center. Surface dull and dry. Margin slightly exceeding the lamellae. Lamellae free, straight, intercalated with numerous lamellulae, white for a long time, staining pink after bruised, finally brown at maturity. Stipe 10–14 × 0.9–2 cm, cylindrical and bulbous at base, fistulose, tapering at base, fistulose, beige, smooth above annulus, with brown erect scales below, no discoloration when cut. Annulus superous, double, white, membranous, upper surface smooth, lower surface covered with whitish or beige floccose squamules. Context white, firm, no discoloration when cut. Odor of almonds.

Microscopic description: Basidiospores (4.6–)4.8–5.1(–5.3) × 3.1–3.6 (–3.7) μm, (x = 4.9 × 3.4 μm, Q = 1.36–1.56, Qm = 1.43, n = 40), ellipsoid, smooth, brown, without apical pore. Basidia 12–26 × 6–6.5 μm, tetrasporic, clavate, hyaline, smooth. Cheilocystidia abundant, hyaline, simple, pyriform, clavate, obovoid. Pleurocystidia not observed. Lower surface of the annulus composed of hyaline hyphae, cylindrical, not or narrowed at septa, 3.5–13.5(–19) μm wide, few cells inflated. Pileipellis a cutis composed of cylindrical and thin-walled hyphae of 4–12.5 μm wide, hyaline or with brownish membranous pigment, with abundant terminal elements cylindrical or progressively attenuated with rounded apex. Clamp connections not observed.

Macrochemical reactions:—Schäffer’s reaction positive, purplish red. KOH reaction positive, yellow.

Habit and habitat:—scattered in a fairy ring of approximately four meters diam. on grass in a sports field.

Material examined:— MEXICO, Coatepec, Unidad Deportiva Roberto Amorós Guiot. Football field 1, 21 July 2010, G. Mata, MATA816.

Notes:— Agaricus globocystidiatus is characterized by its medium size sporocarps, a pileus surface covered with purplish to brownish scales, a tapering stipe and the presence of cheilocystidia and pleurocystidia. Our Mexican material matches well with the original description, except for the pleurocystidia that we did not observe. Indeed, pleurocystidia has been evidenced in the type specimen, but not in every collection of Brazilian material (pers. communication with M. Drewinski). In addition, our spores are slightly smaller (5.3 × 4.2 μm in Brazilian collections, Drewinski et al. 2017), which can be considered as intraspecific variation.

Figures

FIGURE 4. Macroscopic characteristics of A. globocystidiatus. a–c. Basidiomata (MATA816).

FIGURE 5. Microscopic characteristics of A. globocystidiatus. a–c. (MATA816). a. Basidia; b. Spores; c. Cheilocystidia. Bars = 5 μm.