Agaricus kunmingensis

Agaricus kunmingensis R.L. Zhao.

Index Fungorum number: IF 570221, MycoBank: MB 570221, Faces of Fungi: FoF01188

Pileus 20–35 mm in diam, 5 m thick at the disc, campanulate when young, convex to subumbonate when open, with flat top, 45–70 mm in diam.; surface dry, covered by heavy fibrils completely at first, then broken into slightly recurved, more or less concentric, brown (oac700), light brown (oac683) squamules, on a white background, discolouring reddish brown on touching; margin decurved and exceeding. Lamellae free, 3–6 mm broad, some slightly ventricose, crowded, intercalated with lamellulae, reddish brown (oac599), brown, dark brown with age, Stipe 90–150× 6–7 (apex) – 10–12 (base) mm when mature, ventricose when young, then cylindrical to slightly clavate, hollow, white, surface smooth or slightly fibrillose, white, discolouring reddish brown on touching. Annulus thick membranous, 5–8 mm in diam., entire, pendant or subperonate, upper surface smooth, white and lower surface, heavily floccose, sometimes the floccose layer incompletely white or light brown. Context firm, on cutting at first white to dirty white in both pileus and stipe, then quickly turning reddish brown, finally after 15 min uniformly light brown. Odour pleasant or indistinct. KOH not distinct or slightly reddish brown, Schäffer’s reaction negative. Basidiospores 4.1–5.3× 2.7–3.3 μm [= 4.6 ± 0.3× 3 ± 0.2, Q= 1.4–1.7, Qm= 1.5 ± 0.1, n=20], ellipsoid, brown, smooth, thick-walled, without germ pore. Basidia 17–23×6–7.7 μm, clavate, hyaline, smooth, 4-spored. Cheilocystidia abundant in young fruiting body and less when mature, pyriform, broad clavate, 14–25 × 8–16 μm, smooth, hyaline. Pleurocystidia absent. Pileipellis a cutis composed of 6–15 μm in diam. hyphae, slightly constricted at the septa, containing light brown to brown pigments. Annulus composed of 3–9 μm diam., hyaline, branched, cylindrical hyphae. (Fig.1 h-j; Fig. 2)

Etymology: the epithet “kunmingensis” refers to the region “Kunming” from where the holotype was collected.

Holotype: CHINA, Yunnan Prov., Kunming, Yeya Lake, 30 June 2012, collected by R.L. Zhao, ZRL 2012007 (HMAS273970, holotype).

Habitat: scattered in mixed forests of Ericaceae and Fagaceae.

Specimen examined: CHINA, Yunnan Prov., Kunming, Yeya Lake, 30 June 2012, collected by R.L. Zhao, ZRL 2012007 (HMAS273970, holotype).  Yunnan Prov., Kunming, Yeya Lake, 30 June 2012, collected by R.L. Zhao, ZRL2012015(HMAS273942).

Distribution: China.

Notes: These three species differ from A. magnivelaris Pegler as the latter has oblong-ellipsoid basidiospores (Qm = 1.9), while the spores of all new species are ellipsoid with a Qm = 1.5–1.6. The basidiomes of the new species are more or less reddish brown on touching or cutting or in KOH reaction, but in A. variabilicolor and A. dolichopus discolouration is very weak or indistinct; while A. kunmingensis has a distinct reddish brown discolouration in all cases. In the field, A. variabilicolor has a light brown cap which is not darker at the disc of pileus, and has a floccose stipe surface, while A. dolichopus has distinct brown triangular scales, which are darker at the disc, and a smooth to slightly fibrillose stipe surface.