Agaricus microviolaceus

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

Fungal Names: FN570343; Faceoffungi Number: FoF 02931

Pileus 18–26 mm in diam., convex, plane; disc slightly umbonate; margin straight, with appendiculate remains of universal veil; surface dry, covered by fibrils and forming fibrillose scales, denser at disc, scattered towards the margin, appressed, purple, reddish brown, fading into white towards margin. Context 1–2 mm thick, flesh, white. Lamellae 2–3 mm broad, free, crowded, pink or pinkish brown firstly, then brown, edge crenate, intercalated with lamellulae. Annulus 3 mm in diam., single, membranous, white, pendant, upper surface smooth, lower surface fibrillose. Stipe 30–66 × 2–3 (3–4 at base) mm, white, hollow, cylindrical, surface dry, surface below the annulus fibrillose. Odour of almonds. Basidiome strongly yellow then orange brown after several minutes when touching, bruising and cutting. KOH reaction: positive yellow. Schäffer’s reaction: positive, reddish orange on dry specimen. Basidiospores 4.6–6.2 × 3.0–3.6 μm, [x = 5.2 ± 0.4 × 3.3 ± 0.2, Q = 1.3–1.8, Qm = 1.6 ± 0.1, n = 20], ellipsoid, elongate, smooth, thick-walled, brown. Basidia 11.8–18.2 × 5.4–7.0 μm, clavate, hyaline, 4-spored, smooth. Cheilocystidia 7.6–26.4 (−47.8) × 5.6–10.6 μm, smooth, single, clavate mostly, broadly clavate, hyaline or containing yellow pigments. Pleurocystidia absent. Pileipellis a cutis composed of hyphae of 4.5–10 μm in diam., smooth, cylindrical, hyaline, having yellow or light brown pigments.

Habitat: solitary on soil in forest.

Other specimens examined: Dalongkou, Yimen County, Yunnan Prov., China, 17 August 2012, collected by Xie Meng, ZRL2012716 (HMAS275790), ZRL2012717 (HMAS275792), ZRL2012714 (HMAS273969).

Notes: In our phylogeny analysis, A. microviolaceus is represented by three specimens which nest together with the support of 1.0/100 PP/BS values. Agaricus microviolaceus cluster with other three unnamed specimens (ZRL3056, ZRL2011039, and LD201252) and composed of clade VI with the support of 1.0/100 PP/BS values (Figs 1–2). This new species is characterized by its slender basidiome, purple fibrillose scales on the cap and clavate cheilocystidia which contains yellow pigments. This combination of morphological characters make it similar to another introduced new species A. mangaoensis in this study and A. gemloides 5. In the field, this new species can separated from A. mangaoensis by the latter has much darker fibrils on the cap and bulbose stipe. Compared with A. gemloides, the capitated cheilocystidia of A. gemloides is distinct morphological character to separate from A. microviolaceus.

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.