Agaricus blatteus

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

Fungal Names: FN570357; Faceoffungi Number: FoF 02921

Pileus 13–28 mm in diam., plane, disc subumbonate; margin straight, slightly uplifted when mature; surface dry, covered by fibrils completely, and form fibrillose scales, triangular, appressed, denser at disc, scanty towards the margin, dark purple, purple brown; fibrils often rubbed by rain drops; background white or light gray. Context up to 1 mm thick, flesh, white. Lamellae 2 mm broad, far free, crowded, broad, light brown, dark brown in age, edge even. Annulus 1–2 mm in diam., fragile, membranous, single, white, pendant. Smooth at the both sides. Stipe 25–51 × 1–6 mm, white, cylindrical, hollow; surface dry, smooth. Odour of almonds. Basidiome flavescent when touching, bruising and cutting. KOH reaction: positive yellow; Schäffer’s reaction: positive, reddish orange on dry specimen. Basidiospores 4.1–4.9 × 3.0–3.5 μm, [x = 4.5 ± 0.2 × 3.3 ± 0.1, Q = 1.2–1.5, Qm = 1.4 ± 0.1, n = 20], ellipsoid, smooth, thick-walled, brown. Basidia 13.4–17.3 × 5.3–7.0 μm, clavate, hyaline, 4-spored, smooth. Cheilocystidia 12–33.3 × 6.6–14 μm, smooth, mostly pyriform and broad clavate, some ellipsoid, with yellow pigment inside. If the terminal element appears, cylindrical most, rarely clavate. Pleurocystidia absent. Pileipellis a cutis composed of hyphae of 3.3–11.5 μm in diam., smooth, cylindrical, light brown, slightly constricted at septa.

Habitat: solitary on soil in forest.

Specimens examined: Gantong Temple, Dali, Yunnan Prov., China, 1st August 2014, collected by He Mao-Qiang, ZRL2014282 (HMAS275774).

Notes: Agaricus blatteus is characterized by its small basidiome and dark purple fibrils on the cap. In the phylogeny, A. blatteus represented by specimen ZRL2012004 is sister to another new species A. dilatostipes and forms a clade under the supports of 1.0/91 PP/BS values. But in the morphology, A. blatteus is obviously different from A. dilatostipes by its small basidiome which of A. dilatostipes is lager sized (44–110 mm diam. in cap). Combined this new species with all known species of section Minores in morphology, A. purpurellus F.H. Møller and A. parvibicolor L.J. Chen, R.L. Zhao & K.D. Hyde are two most similar species because they all have purplish fibrils on pileus, and the same basidiospores in size and shape. However, A. purpurellus has a middle-sized basidiome (pileus 20–50 mm in diam.)4, which A. blatteus has much smaller basidiome (pileus 13–28 mm in diam.). Cheilocystidia of A. parvibicolor are capitate with long narrow stipe, while those of A. blatteus are pyriform and broad clavate19. Furthermore, the phylogenetic analysis also indicates this new species is different species from all known species.

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.