Agaricus luteofibrillosus – Facesoffungi number: FoF 02036

Agaricus luteofibrillosus M.Q. He, L.J. Chen & R.L. Zhao

Fungal Names number: FN570234 Faces of fungi number: FoF 02036

Etymotogy: the epithet Bluteo^ refer to the yellow colour; and Bfibrillosus^ refers to the fibrils on the pileus and stipe.

Holotype: HMAS 254487

Marcoscopical characters: Pileus 35–94 mm in diam., parabolic at first, then convex, finally plane, sometimes with slightly subumbonate disc with age; margin slightly decurved when young, then straight; surface dry, fibrillose, yellowish brown against white to light brown background, fibrils appressed, denser at disc, then broken into triangular fibrillose squamules towards the margin.Context 3–8 mm thick atdisc, fresh, white, and yellow discolouring on exposure. Lamellae 4–8 mm broad, free, crowded, pink when young, then brown when mature. Annulus simple, membranous, pendant, white, lower surface floccose with light brown tiny squamose. Stipe 60–141×5–14 (base 8–25) mm, white, cylindrical, base clavate or subbulbose, surface smooth and white above the annulus, fibrillose squamose or floccose and light brown below the annulus, hollow. Basidiome surface yellow discolouring on touching or bruising. Odour of almonds.

Macrochemical reaction: KOH reaction strongly yellow; Schäffer’s reaction orange.

Microscopical characters: Basidiospores5–6.5(–7.2)×3– 4.2 μm [x=5.8±0.4×3.4±0.2, Q=1.5–2, Qm=1.7±0.1, n=20], ellipsoid to cylindric, smooth, thick-walled, brown, no germ pore. Basidia 14–18×5.6–7.3μm, clavate, hyaline, 4-spored, smooth. Cheilocystidia 9.4–28×6.4–17 μm, mostly globose and clavate, sometimes pyriform and pheropedunculate, septa at base sometimes, smooth, hyaline, some with yellow pigment inside. Pleurocystidia absent. Pileipellis a cutis composed of hyphae of 3.2–13.2μm in diam., smooth, cylindrical, light brown, constricted at septa. Annulus composed of hyphae with 3–9.5μm in diam., hyaline, cylindrical, not constricted at septa.

Habitat: Solitary on soil of forest.

Material examined: CHINA, Yunnan Province, Baoshan, Gaoligong Mountain, Wanzi Village, He Mao-Qiang ZRL 2013484 (HMAS 254487, holotype); Yunnan Province, Yongde County, Pingtian Village, Li Guang-Ping ZRL 2012359 (HMAS 275419); Yunnan Province, Cangyuan County, Nanban Village, Zhao Rui-lin ZRL 2012121 (HMAS 254486), ZRL 2012200 (HMAS 275415).

Notes: In the phylogenetic tree, the proposed new species A. coccyginus and A. luteofibrillosus are represented by two clades respectively with strong PP and BS support. Their phylogenetic positions are also clearly distinguished from other known species in section Minores. In morphology, they both have related larger basidiomes which the cap reaching 110 mm in diam. There are only two species with such large-sized basidiomes in section Minores, one is A. brunneolus (J.E. Lange) Pilát and the other is A. megalosporus J. Chen et al. Agaricus brnneolus is the most similar species to A. coccyginus. They both have the same shape of cap, stipe and same colour of fibrils on the basidiome. Also, under the microscope they have the similar cheilocystidia. There are some distinguishable autapomorphies between these two species. Agaricus coccyginus has the longer basidiospores than those of A. brunneolus (length 4.5–6.2μm). The yellow pigment of cheilocystidia in A. coccyginus is also another difference from A. brunneolus. Agaricus megalosporus is the most similarspeciesto A. luteofibrillosus, because both species have similar basidiomes, they both have coloured fibrils on the cap, annulus and stipe. Both have the same size of basidospores, but Agaricus luteofibrillosus has a yellowish brown cap, while in A. megalosporus it is purplish brown. Under the microscope they have different cheilocystidia: in A. megalosporus they are broadly clavate to pyriform, and white, while in A. luteofibrillosus they are pheropedunculate, septa at base and contain yellow pigment.