Pseudolepiota zangmui Z.W. Ge in Ge and Yang
Index Fungorumnumber: IF 820482; Facesoffungi number: FoF 07068.
Pileus 20–50 mm, at first hemispherical, campanulate, expanding to convex, umbonate or often plano-convex with an umbo and inflexed margin; surface covering violet-brown (10F5-8, 11F-8), darker at umbo or center, dark ruby to dark (12F4–8), smooth or rough, later splitting off and becoming irregularly concolorous squamulose, with larger scales around the umbo and with smaller squamules toward the margin, with dull red (9B3–4) fibrillose or fibrillose squamules at the marginal zone on a white to orange-white (6A2) background; squamules are fragile when mature; margin appendiculate, with white to dull red (9B3–4) fibrillose remnants. Lamellae free, at first white, turning yellowish-white when mature and greyish-orange (5B3–4) when dried, 3.5–5 mm wide, crowded, with 4–5 lamellulae in between lamellae, slightly fragile with age, with an eroded edge. Stipe 25–40 × 5–8 mm, equal, slightly wider at base zone, completely covered by white to yellowish-white fibrils, sometimes with white remnants at the annular zone. Annulus a
white annular zone. Context white in pileus, up to 4 mm wide, white in the stipe, changing to reddish with age, hollow. Spore print whitish. Taste and smell not observed.
Basidiospores [2,2,50] 4.8–5.2 × 3.5–4.5 µm, avl × avw = 5.0 × 4.0 µm, Q = 1.15–1.37, Qav = 1.25, in side-view broadly ellipsoid to ellipsoid-ovoid, in frontal view broadly ellipsoid to ellipsoid, hyaline to pale-yellow in water and KOH, slightly thick-walled without a germ pore, dextrinoid, congophilous, cyanophilous, not metachromatic. Basidia 15–18 × 4.8–5.0 µm, clavate, 4-spored, some 2-spored. Lamella edge sterile. Cheilocystidia 15–24 × 6–10 µm, most clavate, some with a long stalk, rarely utriform and sphaeropedunculate, thin-walled, hyaline. Pleurocystidia absent. Pileus covering hymenoderm made up of 3–4 layers of elements, oblong to cylindrical in the lower layer, mostly with clavate, rarely subclavate, elements in the upper layer, 12–30 × 5.0–10 µm, thick-walled, smooth and with hyaline to pale-yellow parietal pigments, with brown intracellular pigments and encrusted walls in some lower elements. Clamp connections absent.
Habitat and distribution: in small to large groups, saprotrophic and terrestrial in deciduous forests dominated by Lithocarpus spp. and Castanopsis spp. at 650–950 m alt. Found in China and Thailand.
Material examined: THAILAND, Chiang Rai Province, Muang District, Forest of Hua Doi Village, 23 September 2009, P. Sysouphanthong, PHO25 (MFLU 10-0515); ibidem, 25 September 2009, P. Sysouphanthong, PHO28 (MFLU 10-0518); Chiang Rai Province, Muang District, Mae Fah Luang University Campus, 13 August 2019, P. Sysouphanthong, PS2019-74 (MFLU 19-2360). Chiang Mai Province, Mae Taeng District, Pha Deng Village, alt. 900–950 m, 7 August 2018, P. Sysouphanthong, PS2018-84 (MFLU 19-2355).
Notes: Pseudolepiota zangmui is characterized by squat basidiomata in which the pileus diameter is equal or slightly longer than the stipe length; the pileus is covered in violet-brown to dark ruby squamules with dull red fibrils between squamules, and it has a white appendiculate margin; the basidiospores are pale-yellow, and oblong-ovoid in side-view, the cheilocystidia are clavate, and the pileus covering is hymenidermal. The type of Pseudolepiota zangmui was described from Xishuangbanna, Yunnan Province,
Southwest Yunnan, China; it closely resembles Xanthagaricus species but differs in the white to pale-cream spore print and the squat basidiomata. Based on phylogenetic analyses of combined ITS and LSU data with a wide sampling of Xanthagaricus species, it is closely related and basal to Xanthagaricus with good support. However, in a phylogenetic analysis including protein-coding genes, Pseudolepiota is clearly separated from Xanthagaricus.