Macrolepiota mastoidea (Fr. : Fr.) Singer in Lilloa 22: 417. 1951 (‘1949’). Agaricus mastoideus Fr. : Fr., Syst. mycol. 1: 20. 1821. Lepiota mastoidea (Fr. : Fr.) P. Kumm., Führ. Pilzk.: 135. 1871. Lepiotophyllum mastoideum (Fr. : Fr.) Locq. in Bull.

mens. Soc. linn. Lyon 11: 40. 1942. Leucocoprinus mastoideus (Fr. : Fr.) Locq. in Bull. mens. Soc. linn. Lyon 14: 46. 1945. Basidiomata (Fig. 4a) medium-sized to large. Pileus 5–11 cm in diam., fleshy, ovoid when young, becoming convex to plano-convex when mature, with a distinct umbo at disc, white to off-white, covered with grey-brownish furfuraceous squamules, which are at first smooth and continuous, then gradually break up into irregular patches, and become minute and sparse toward margin; margin slightly appendiculate. Lamellae free, crowded, CH5424802 white to greyish white, with lamellulae of 2–3 lengths. Stipe subcylindrical, 6–15 × 0.5–1.0 cm, KU55933 solubility dmso attenuating upwards, whitish, covered with tiny furfuraceous brownish squamules, especially above the annulus; base slightly enlarged. Annulus

ascending, simple, whitish, membranous. Context whitish, not changing color when cut. Taste mild. Fig. 4 Macrolepiota mastoidea (HKAS 11084) a. Basidiomata; b. Squamules on pileus; c. Basidiospores; d. Basidia; e. Cheilocystidia Basidiospores (Fig. 4c) [41/2/2] (11.0) 12.0–14.0 (15.0) × 8.0–9.5 (10.0) μm, x = 12.95 ± 0.84 × 8.69 ± 0.60 μm, Q = (1.33) 1.38–1.63 (1.65), avQ = 1.49 ± 0.09, ellipsoid to ovoid in side view, ellipsoid in front view, thick-walled, Ilomastat concentration smooth, hyaline, dextrinoid, congophilous, metachromatic in cresyl blue, with a germ pore caused by an interruption in the episporium on the rounded apex, covered with a hyalinous cap in KOH; apiculus 1–1.5 μm long. Basidia (Fig. 4d) 32–44 × 12.0–14.0 μm, clavate, thin-walled, hyaline, 4-spored. Cheilocystidia

(Fig. 4e) (10) 15–20 × 7–10 μm, clavate, hyaline, thin-walled, in bunches forming a sterile edge. Pleurocystidia absent. Squamules on pileus (Fig. 4b) a palisade of subcylindric, clampless hyphae (6–12 μm in diam.), with terminal elements slightly attenuate toward the Calpain tip, with yellowish to brownish vacuolar pigment, slightly thick-walled. Clamp connections occasionally observed at the base of basidia. Habitat and known distribution in China: Terrestrial and saprotrophic, solitary to scattered in open meadows or in mixed forests. Distributed in northeastern and southwestern China. Materials examined: Heilongjiang Province: Yichun City, Beishan, alt. 400 m, 8 Aug. 2000, M. S. Yuan 4646 (HKAS 37384); Huma County, 29 July 2000, X.L. Mao, H.A. Wen and S.X. Sun 120 (HMAS 76557, determined as Macrolepiota crustosa L.P. Shao & C.T. Xiang by Mao). Jilin Province: Antu County, Baima town, alt. 740 m, 17 Aug.