Agaricales » ‎Agaricaceae » Agaricus

Agaricus globosporus

Agaricus globosporus M.Q. He & R.L. Zhao

Fungal Names: FN570351; Faceoffungi Number: FoF 02929

Pileus 11–62 mm in diam., parabolic first, then convex, finally plane with age; margin incurved when young, then decurved, finally can be uplifted in age, margin exceeding; surface dry, covered by reddish brown, purple fibrils against white background; fibrils often break into triangular fibrillose scales at disc, appressed; sometimes cracking; turn reddish black in wet. Context 5–8 mm thick, flesh, white. Lamellae 3–15 mm broad, free, crowded, pink or pinkish brown, then brown, edge even, intercalated with lamellulae. Annulus 4–8 mm in diam., single, membranous, white, pendant, smooth on both sides. Stipe 22–48 × 6–15 (8–14 at base) mm, white, hollow, clavate when young, then cylindrical, surface dry, slightly fibrous. Odour of almonds. Basidiome strongly flavescent when touching and bruising. Yellowish discoloration on cutting. KOH reaction: positive yellow. Schäffer’s reaction: positive, reddish orange on dry specimen. Basidiospores 4.2–5.7 × 3.9–4.6 μm, [x = 5.0 ± 0.3 × 4.3 ± 0.2, Q = 1.0–1.3, Qm = 1.2 ± 0.1, n = 20], globose, broadly ellipsoid, smooth, thick-walled, brown. Basidia 24.6–38.6 × 8.8–11.6 μm, clavate, hyaline, 4-spored, smooth. Cheilocystidia 15–37.4 × 5.4–19.7 μm, smooth, hyaline, clavate mostly, broadly clavate or capitate with long narrow stipe, and base septate. Pleurocystidia absent. Pileipellis a cutis composed of hyphae of 2.7–6.8 μm in diam., smooth, cylindrical, brown, slightly constricted at septa.

Habitat: solitary or gregarious on plateau grassland.

Other specimens examined: Bangda Grassland, Basu County, Tibet, China, 4 August 2012, collected by Zhao Rui-Lin, ZRL2012652 (HMAS275782), ZRL2012653 (HMAS275795); Wulashan Grassland, Mangkang County, Tibet, China, 5 August 2012, collected by Dong Xin-Yu, ZRL2012658 (HMAS275749).

Note: Agaricus globosporus is represented by a clade composed of two specimens (ZRL2012652, ZRL2012656) under the fully support of 1.0/100 BS/PP values. This new species clustered with A. armandomyces, A. kerriganii and A. edmondoi under the support of 0.9/- PP/BS values in clade I. In morphology, A. globosporus resembles A. brunneolus (J.E. Lange) Pilát and A. comtulus Fr., because they all have brown pileus, cylindrical to clavate stipe, and similar cheilocystidia in shape and size. However A. globosporus has near globose basidiospores (Q = 1.0–1.3), while those of A. brunneolus and A. comtulus are broadly ellipsoid (Q = 1.2–1.6)4.

Fig. 1 Maximum Likelihood (ML) tree of Agaricus section Minores based on LSU, tef1-α, rpb2 and ITS sequences with the outgroup Agaricus campestris. The Bayesian posterior probabilities and bootstrap support values more than 0.9/50% (PP/BS) are indicated at the nodes. The branches in Bold mean the related PP > 0.95. Sequences produced from this study are in blue. “T” refers to sequences from type specimen, and “T” in red refers to the sequences from type specimen and new to science from this study.