Agaricales » ‎Agaricaceae » Agaricus

Agaricus candidolutescens

Agaricus candidolutescens Linda J. Chen & R.L. Zhao

Index Fungorum number: IF 570195, Mycobank: 570195, Facesoffungi number: FoF01170

       Pileus 27–42 mm diam., 2 mm broad at disc, convex to applanate; surface dry, smooth, silky, with woolly-fibrillose squamules towards the margin, pure white; margin appendiculate. Lamellae free, crowded, ventricose, intercalated with lamellulae, with more than 5 series, 2.5–4 mm broad, at first pink, then pinkish brown, later dark brown and finally almost black. Stipe 40–55 × 3–8 (10–12 at base) mm, cylindrical with a bulbous base, narrowly hollow, white, staining yellow when bruised, smooth above the ring, fibrillose below the ring. Annulus membranous, simple, white, fragile, upper side smooth, lower side fibrillose. Context firm, at first white on cutting, both in pileus and stipe, and quickly turning yellow at the stipe base, finally after 15 min uniformly brown. Odour of almonds. Macrochemical reactions: KOH reaction positive yellow, Schäffer’s reaction negative. Basidiospores 6.4–7.3 (−7.5) × 3.9–4.5 μm, [x = 6.8 ± 0.32 × 4.2 ± 0.2, Q = 1.49–1.77, Qm = 1.6 ± 0.05, n = 20], ellipsoid, smooth, dark brown, thick-walled, without germ pore. Basidia11–13 × 6.5–8 μm, clavate, hyaline, smooth, 4-spored. Cheilocystidia 18–38 × 7.5–13 μm, rare, simple, pyriform or sphaeropedunculate, hyaline, smooth. Pleurocystidia absent. Pileipellis a cutis composed of hyphae 5–9 μm in diam., cylindrical, hyaline, smooth, at times slightly constricted at the septa. (Figs. 1–2)

Etymology: “candido” refers to the white surface of basidiome; “lutescens” refers to slightly yellow of context on cutting.

Holotype: THAILAND, Chiang Rai Prov., Doi Pui, 25 July 2012, collector Jie Chen, LD2012129 (MFLU12-0962, holotype; HMAS373994, isotype).

            Habitat: in groups, in rich soil of tree stump.

Specimens examined: THAILAND, Chiang Rai Prov., Doi Pui, 25 July 2012, collector Jie Chen, LD2012129 (MFLU12-0962, holotype; HMAS373994, isotype).

 

Fig. 1 Macrocharacters of A. candidolutescens (specimen LD2012129, Type a, b), A. crassisquamosus (specimen ZRL2012607, Type, c, d); A. trisulphuratus complex (specimen ZRL3073, e, f), and A. ignicolor (specimen ZRL2132, Type, g–i)

Fig. 2 Microcharacters of A. candidolutescens L.J. Chen & R.L. Zhao (LD2012129). a. Cheilocystidia b. Basidia c. Basidiospores, bars a, b, c=5 μm

Reference

Zhao RL, Zhou JL, Chen J, Margaritescu S, Sánchez-Ramírez S, Hyde KD, Callac P, Parra LA, Li GJ, Moncalvo JM 2016 –Towards standardizing taxonomic ranks using divergence times—a case study for reconstruction of the Agaricus taxonomic system. Fungal Divers 78:239–292.

 

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Supported by 
National Research Council of Thailand (NRCT) 

Project entitled:
“Total fungal diversity in a given forest area with implications towards species numbers, chemical diversity and biotechnology” (Grant no. N42A650547).

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