Agaricales » ‎Agaricaceae » Agaricus

Agaricus cerinupileus

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

Fungal Names: FN570358; Faceoffungi Number: FoF 02924

Pileus 70–90 mm in diam., parabolic with flat top when young, then applano-convex, finally plane with umbo, margin eroded mostly, or straight, margin exceeding with white appendiculate elements of universal veil; surface dry covered by fibrils at whole cap; background white or light yellow, turn red in wet; fibrillose scales ochraceous-yellow, triangular, appressed, denser on disc, radially scattered towards the margin. Context 2–8 mm thick, flesh, white, brown in old. Lamellae 3–7 mm broad, free, crowded, pink or pinkish brown firstly, then brown, edge even, normal to ventricose, intercalated with lamellulae. Annulus 8–15 mm in diam., single, membranous, pendant, smooth on both sides, white, turn yellow when dry or old. Stipe 47–128 × 6–65 (11–90 at base) mm, white or ochraceous-yellow, hollow, long clavate, surface dry, above the annulus smooth, below heavily fibrillose-woolly especially when young. Odour of almonds. Basidiome flavescent when touching, bruising and cutting. KOH reaction: positive yellow; Schäffer’s reaction: positive, reddish orange on dry specimen. Basidiospores 5.5–6.5 × 3.5–4.2 μm, [x = 6.0 ± 0.3 × 3.5 ± 0.2, Q = 1.4–1.7, Qm = 1.6 ± 0.1, n = 20], ellipsoid, elongate, smooth, thick-walled, brown. Basidia 13.4–22 × 5.4–7 μm, clavate, hyaline, 4-spored, smooth. Cheilocystidia 18.6–44 (−48) × 11–25 μm, smooth, capitate with long narrow stipe mostly, or globose, clavate, broadly clavate, hyaline or containing yellow pigments. Pleurocystidia absent. Pileipellis a cutis composed of hyphae of 3.3–7.4 μm in diam., smooth, cylindrical, brown, slightly constricted at septa.

Habitat: solitary on soil in forest.

Other specimens examined: Gaoligongshan, Baoshan, Yunnan Prov., China, 21 July 2011, collected by Zhao Rui-Lin, ZRL2011157 (HMAS280107); China, Yunnan Prov., Kunming, Kunming Institute of Botany, 15 Sep 2012, collected by Zhou Jun-Liang, ZRL2012725 (HMAS275757).

Notes: In our phylogeny analysis (Figs 1–2), the proposed new species A. cerinupileus was represented by four specimens, and they cluster together under the support of 1.0/100 PP/BS values in the clade XI. The phylogenic closest species is A. luteopallidus L.J. Chen, Karunarathna, R.L. Zhao & K.D. Hyde10. In morphology, the stipe surface of A. luteopallidus is slightly fibrillose, while A. cerinupileus is heavily fibrillose especially when young. There are also several species with yellowish brown caps, such as A. luteofibrillosus M.Q. He, L.J. Chen & R.L. Zhao, A. luteoflocculosus Kalaméés and A. fulvoaurantiacus L.J. Chen & Karunarathna4, 8, 10. Agaricus cerinupileus is a different species from A. luteofibrillosus and A. fulvoaurantiacus because the later two species nest in the Clade III based on the phylogeny (Figs 1–2). In morphology, A. cerinupileus differs from A. fulvoaurantiacus by its heavily fibrils on the stipe surface below the annulus, while those of A. fulvoaurantiacus is weak10; differs from A. luteoflocculosus by its capitate cheilocystidia and larger basidiospores, while those of A. luteoflocculosus are simple cheilocystidia and basidiospores 5.1–5.3 × 3.4–3.7 μm4. In summary, this new species is characterized by its pileus orchraceous-yellow, cheilocystidia capitate with long narrow stipe and containing yellow pigments.

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.