Agaricales » ‎Agaricaceae » Agaricus

Agaricus jingningensis

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

Fungal Names: FN570356; Faceoffungi Number: FoF 02923

Pileus 32–78 mm in diam., convex first, plane with age; disc umbonate, margin straight, also can be uplifted in age, margin slightly exceeding; surface dry, covered by plenty of fibrils at whole cap, fibrils can be rubbed by raindrop; background white or gray, get red in wet; fibrillose scales reddish brown or purplish brown, denser at disc, scanty obviously towards the margin; tiny fibrillose scales triangular-shaped, appressed, or erected. Context 3–4 mm thick, flesh, white or light gray. Lamellae 4–5 mm broad, free, crowded, edge even, pinkish brown to brown in age, intercalated with lamellulae. Annulus up to 10 mm in diam., fragile, membranous, single, white, pendant, smooth on both sides. Stipe 60 × 5–7 (10–11 at base) mm, white, hollow, cylindrical, slightly bulbous at base, surface dry, with white fibrils below the annulus. Odour of almonds. Basidiome flavescent when touching and bruising, then becoming orange brown after several minutes. No discoloration or slightly yellowish on cutting. KOH reaction: positive yellow; Schäffer’s reaction: positive, reddish orange on dry specimen. Basidiospores 4.3–5.2 × 3.0–3.6 μm, [x = 4.8 ± 0.3 × 3.3 ± 0.1, Q = 1.3–1.6, Qm = 1.4 ± 0.1, n = 20], ellipsoid, smooth, thick-walled, brown. Basidia 12.8–18.4 × 5.5–7.6 μm, clavate, hyaline, 4-spores, smooth. Cheilocystidia 14.5–32 × 7–17 μm, smooth, clavate and ellipsoid. Septa at base sometimes, with yellow pigment inside. Pleurocystidia absent. Pileipellis a cutis composed of hyphae of 5.5–14 μm in diam., smooth, cylindrical most, brown, terminal element ellipsoid, constricted at some septa.

Habitat: solitary on soil in forest.

Other specimens examined: Yingjiang County, Yunnan Prov., China, 21 July 2013, collected by Yu Qing-Hua, ZRL2013405 (HMAS275752); Shigu, Lijiang, Yunnan Prov., China, 31 July 2014, collected by Su Sheng-Yu, ZRL2014248 (HMAS275775).

Notes: In our phylogeny analysis, the proposed new species clusters with A. catenatus (another new species from this study) in clades IX under the support of 1.0 PP value. Compared with A. catenatus, they are sharing the same sized basidiome, similar basidiospores in shape and size, however the cheilocystidia of A. catenatus are various in shape and often in chains, and those of A. jingningensis is simple. In the field, they can also be easily separated from A. catenatus having a nearly white pileus. Agaricus pallens (J.E. Lange) L.A. Parra is another species which resembles this new species, because both of them have relative slender basidiome, similar characters in pileus and basidiospores. However, the cheilocystidia of A. pallens is septa at base or multiseptate mostly, which is different from A. jingningensis 4. Then we proposed A. jingningensis as a new species, and is characterized by its reddish brown fibril scales at the disc of cap, slender basidiome and simple cheilocystidia.

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.