China. Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Tekes County, Aktamu Wetland, 43°15'22.61"N, 81°75'90.21"E, alt. 1243 m, 6 July 2022, Z.X. Qi (FJAU 66134, holotype!).

ITS: PP002167, TEF1-α: PP062823.

“brunneo-”: brown, “-discus”: pileus disc. The species epithet “brunneodiscus” (Lat.) refers to the brown of the middle part of the pileus disc.

Pluteus brunneodiscus differs from P. tomentosulus by its brown pileus in the middle, transitioning to white toward the margins, and the surface cracks to form irregular granules. It grows in poplar forests (Populus alba var. pyramidalis Bge) with decaying wood branches or chips.

Basidiomata medium to large. Pileus 39–71 mm in diam, initially compressed hemispherical, surface with dense brown irregular granules (5.0YR 5/2), dirty white (5.0YR 9/2), middle brown (5.0YR 4/4), margin entire, gradually spreading at maturity, pileus middle dark brown (5.0YR 3/6), margin irregularly dehiscent at maturity or after hygrophanous. Context whitish (5.0YR 9/2), odorless, 3–6 mm thick. Lamellae initially dirty white (5.0YR 9/2), becoming flesh-brown to earth-brown at maturity (5.0YR 8/4- 5.0YR 6/4), free, dense, thick, unequal, slightly ventricose, 6–7 mm wide. Stipe 37–55 mm long, 8–11 mm wide, dirty white (5.0YR 9/2), cylindrical, slightly thicker at the base, fibrous, with white longitudinal stripes on the surface. Odorless. Spore prints pink.

Basidiospores [120, 12, 3] (–6.5) 7.0–7.5 (–8.0) × 5.0–6.0 (–6.5) µm, avL × avW = 7.0 × 6.0 µm, Q = 1.16–1.30–1.45 µm, avQ = 1.16 µm, globose, subglobose, slightly pink, smooth, thin-walled, non-dextrinoid, partially containing one droplet or irregular inclusions. Basidia 25–32 × 7–11 μm, fusiform to clavate, thin-walled, 4–sterigmate, and hyaline in KOH. Pleurocystidia abundant, scattered, 55–102 × 22–36 μm, vesicular to narrowly vesicular, or clavate, thin-walled, smooth, and hyaline in KOH. Cheilocystidia abundant, clustered, 41–79 × 18–29 μm, subfusiform to fusiform, or ventrally bulbous, apically broadly digitate 15–23 μm long, thin-walled, hyaline. Lamellar trama divergent. Pileipellis a cutis to trichodermium, hyphae 4–10 µm diam, cylindrical, hyaline, non-gelatinous; terminal cells inflated, 62–91 × 22–31 μm, obtusely rounded or pointed apically, thin-walled, with brown cytoplasmic pigments. Stipitipellis a cutis, hyphae 5–9 µm diam, cylindrical, hyaline, non-incrusted, non-gelatinous, thin-walled. Caulocystidia absent. Clamp connections absent in all tissues.

Solitary to scattered on the ground in the broad-leaved forests (Populus alba var. pyramidalis Bge) with decaying wood branches or wood chips. Known from Xinjiang Uygur Autonomous Region of China.

China. Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Tekes County, Aktamu Wetland, 43°15'22.61"N, 81°75'90.21"E, alt. 1243 m, 6 July 2022, Z.X. Qi, D.M. Wu, N. Gao and B.K. Cui, FJAU 66132 (ITS: PP002168, TEF1-α: PP062821). China. Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Tekes County, Aktamu Wetland, 43°15'22.61"N, 81°75'90.21"E, alt. 1243 m, 6 July 2022, Z.X. Qi, FJAU 66133 (ITS: PP002169, TEF1-α: PP062822).

Morphologically, Pluteus brunneodiscus is very similar to P. tomentosulus in having a white pileus. The difference lies in the surface texture, as P. tomentosulus has a very finely granular-tomentose surface that becomes bald at maturity, while P. brunneodiscus features a brown center of the pileus, transitioning to white toward the margins, with the surface cracking to form irregular granules (Vellinga and Schreurs 1985; Orton 1986; Vellinga 1990; Desjardin and Perry 2018).

In phylogenetic analyses, P. brunneodiscus clusters in the ephebeus clade as a sister species to P. aff. ephebeus, and has a support ratio of 1/100. However, the pileus of P. aff. ephebeus are sooty, shield-shaped fruiting bodies with pubescent or downy surfaces. They grow on rotting wood or stumps and are widely distributed in Britain and Ireland (Orton 1986; Justo et al. 2011a; Menolli et al. 2015). These characteristics distinguish P. brunneodiscus from P. aff. ephebeus.

Basidiomata medium to large. Pileus 25–41 mm in diam, compressed hemispherical, surface spreading when young, surface with longitudinal vein-like folds from middle to margin when mature, margin mostly transverse folds, light brown to dark brown (5.0YR 5/6-5.0YR 4/12), margin entire. Context dirty white (2.5YR 9/4), odorless, 5–8 mm thick. Lamellae dirty white (2.5YR 9/4), free, dense, thick, unequal, ventricose, 15–18 mm wide. Stipe 30–41 mm long, 12–17 mm wide, cylindrical, slightly thicker at the base, hollow, fibrous, with brown serpentine or crumbly scales on the surface (2.5YR 9/2). Odorless. Spore prints pink.

Basidiospores [200, 10, 2] (–5.0) 5.5–6.0 (–6.5) × (–4.5) 5.0–5.5 μm, avL × avW = 6.0 × 5.0 µm, Q = 1.10–1.20–1.30 μm, avQ = 1.20 μm, spherical, subglobose, slightly pink, smooth, thin-walled, non-dextrinoid, partially containing one droplet or irregular inclusions. Basidia 23–31 × 7–10 μm, clavate, thin-walled, 4-sterigmate, and hyaline in KOH. Pleurocystidia abundant, scattered, 55–102 × 22–36 μm, rod-shaped or subpyriform, vesicular, thin-walled, smooth, and hyaline in KOH. Cheilocystidia abundant, clustered, 37–60 × 15–22 μm, clavate, fusiform or vesicular, thin-walled. Lamellar trama divergent. Pileipellis a hymeniderm or epithelioid hymeniderm, made up of two types of elements; spheropedunculate or pyriform, 27–55 × 24–34 μm; broadly fusiform, inflated-fusiform, lanceolate, narrowly utriform, often mucronate, 56–105 × 11–23 μm; all elements with brown intracellular pigment, often aggregated in spots, slightly thick-walled. Stipitipellis a cutis of cylindrical, hyphae 8–11 μm wide, with pale brown pigment. Caulocystidia common, often in clusters, 36–112 × 9–20 μm, cylindrical, narrowly clavate, narrowly fusiform, spheropedunculate, with brown or yellow-brown pigment. Clamp connections absent in all studied tissues.

Scattered on decaying wood in mixed coniferous forests (Pinus koraiensis Siebold and Zucc).

Canada, the USA, Japan, Russian Far East.

China. Heilongjiang Province, Liangshui National Nature Reserve. 47°11'22.24"N, 128°47'89.11"E, 23 June 2019, D.Z. Guo, FJAU 66556 (ITS: OR994068, TEF1-α: PP062825). China. Heilongjiang Province, Liangshui National Nature Reserve. 47°11'22.24"N, 128°47'89.11"E, 28 June 2019, D.Z. Guo, FJAU 66557 (ITS: PP002166, TEF1-α: PP062826).

Note.Ševcíková et al. (2023) elevated Pluteus seticeps var. cystidiosus to P. cystidiosus based on specimens from the USA, Canada, Japan, and Russia. The present study reports P. cystidiosus as a new record in China. There was almost complete overlap in morphological variation between those reported in the present study and the holotype specimen. Both grow in temperate/cold-temperate forests. However, the basidiospores of the species in the present study were slightly larger, measuring (–5.0) 5.5–6.0 (–6.5) × (–4.5) 5.0–5.5 µm, while those of the holotype specimen were smaller, measuring 4.5–5.5 (–6.2) × 3.5–5.0 µm.

The phylogenetic tree also supports the results of our morphological study, showing that our specimens are clustered in the same branch as those from the USA and Russia, with a support ratio of 1/100.

Basidiomata medium. Pileus 15–22 mm in diameter, surface not spreading, irregularly pitted, smooth, central part umbo, wrinkled or veined, yellow to bright yellow (5.0Y 9/12-5.0Y 9/20), with a hyaline stripe in the central part 3/4 of the way toward the margin, margin entire. Context yellowish (5.0Y 9/8), odor inconspicuous. Lamellae yellow to brownish yellow (5.0Y 9/6- 5.0Y 9/8), free, dense, thick, unequal, ventricose, 6–8 mm wide. Stipe 25–42 mm long, 4–6 mm wide, cylindrical, slightly thicker at the base, fibrous, bright yellow to yellow (5.0Y 9/10-5.0Y 9/18), smooth, with white tomentose dense cilia at the base. Odorless. Spore prints pink.

Basidiospores [90, 3, 1] 5.5–6.0 × (–4.5) 5.0–5.5 μm, avL × avW = 6.0 × 5.0 µm, Q = 1.09–1.20–1.33 μm, avQ = 1.20 μm, globose, subglobose, slightly pinkish, smooth, thinly walled, non-dextrinoid, partially containing one droplet or irregular inclusions. Basidia 23–34 × 7–11 μm, clavate, thin-walled, 4-sterigmate, and hyaline in KOH. Pleurocystidia scattered, 52–78 × 15–24 μm, broad and long-necked vase-like, partly with a long neck, neck with inclusions, thin-walled, smooth, and hyaline in KOH. Chilocystidia abundant, clustered, smaller, 45–66 × 14–21 μm, similar to pleurocystidia, long-necked vase-shaped to fusiform, thin-walled. Lamellar trama divergent. Pileipellis an euhymeniderm of spheropedunculate and subglobose elements 28–67 × 18–41 μm, with brown or light brown, at the center brown to dark brown. Stipitipellis a cutis, hyphae 5–9 μm wide, hyaline, non-gelatinous, thin-walled. Caulocystidia absent. Clamp connections absent in all tissues.

Solitary on decaying wood in mixed coniferous forests.

North America, South America.

China. Heilongjiang Province, Liangshui National Nature Reserve. 47°11'22.24"N, 128°47'89.11"E, 24 June 2019, D.Z. Guo, FJAU 66561 (ITS: OR994065, TEF1-α: PP062824).

Pluteus chrysophlebius was first reported in China. It can be distinguished from other yellow-pileus species such as P. admirabilis (Peck) Peck, P. aurantiacus Murrill, P. melleus Murrill, and P. rugosidiscus Murrill by its yellowish pileus and stipe, as well as its bald pileus texture (Minnis and Sundberg 2010; Malysheva et al. 2016). The phylogenetic analysis also supports the differentiation of species.

In the phylogenetic tree, P. chrysophlebius formed a cluster with TNSF12383 and TNSF12388 in Asia and was sister to SF10-SF12 in the United States, with strong support for both clades.

Basidiomata medium to large. Pileus 20–56 mm broad, compressed hemispherical to spreading, surface with vein-like projections extending to the pileus margin, often with striated dehiscence, with a greasy or almost waxy texture, brown to yellowish-brown (7.5YR 8/8-7.5YR 6/12), margins wavy dehiscence with translucent-striate. Context light yellow (7.5YR 8/12), odorless, 2–3 mm thick. Lamellae yellowish (10.0YR 8/10), free, medium dense, unequal, entire, ventricose, 5–7 mm wide. Stipe 26–41 mm long and 4–8 mm wide, cylindrical, slightly thicker at the base, fibrous, upper part of the stipe white to yellowish (10.0YR 9/8-10.0YR 7/12), smooth, lower part of the stipe with white tomentum, yellow to yellow-brown (10.0YR 8/8-10.0YR 8/12). Odorless. Spore print pale pink.

Basidiospores [120, 4, 2] 7.0–7.5 (–8.0) × 6.0–6.5 µm, avL × avW = 7.0 × 6.0 µm, Q = 1.07–1.25~1.33 µm, avQ = 1.16 µm, globose, subglobose to ellipsoid, transparent to slightly pinkish, smooth, and thin-walled, non-dextrinoid, partially containing one droplet or irregular inclusions. Basidia 27–32 × 8–10 μm, clavate, thin-walled, 4-sterigmate, and hyaline in KOH. Pleurocystidia abundant, scattered, 55–102 × 22–36 μm, rod-shaped or subcylindrical, fusiform, with neck and apical part broader and obtuse, thinly walled, smooth, and hyaline in KOH. Cheliocystidia abundant, clustered, 41–79 × 18–29 μm, pyriform or similarly pleurocystidia shape, thin-walled. Lamellar trama divergent. Pileipellis an euhymeniderm of spheropedunculate and subglobose elements 25–48 × 23–35 μm, with brown or light brown, at the center brown to dark brown. Stipitipellis a cutis, hyphae 6–10 μm wide, hyaline, non-gelatinous, thin-walled. Caulocystidia absent. Clamp connections absent in all tissues.

Solitary to scattered on decaying wood in coniferous forests (Picea schrenkiana Fisch.).

Europe, Americas, East Asia, Africa.

China. Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Tekes County, Jongkushtai Village, 43°12'26.61"N, 81°91'97.21"E, alt. 2139 m, 10 July 2022, Z.X. Qi, J.J. Hu, and B. Zhang, FJAU 66558 (ITS: OR994057, TEF1-α: PP062827). China. Xinjiang Uygur Autonomous Region, Ili Kazakh Autonomous Prefecture, Tekes County, Jongkushtai Village, 43°15'22.61"N, 81°75'90.21"E, alt. 2147 m, 11 July 2022, Z.X. Qi, J.J. Hu, and B. Zhang, FJAU 66559 (ITS: OR994061, TEF1-α: PP062828).

Initially, the description of Pluteus romellii was rather vague (Britzelmayr 1891), stating that P. romellii was similar to P. nanus (Pers.) P. Kumm, with spores measuring 6–7 μm, and found growing in the soil of Bavaria. It is now widely acknowledged that P. romellii is characterized by a brown pileus, yellow stipe, and the absence of elongated elements in the pileipellis. This species is placed on the phylogenetic tree in subsect. Eucellulodermini under sect. Celluloderma (Orton 1986; Vellinga 1990; Ševcíková et al. 2023). Here, our description of the P. romellii is consistent with the commonly accepted characterization. Phylogenetic analysis shows that it clustered with the epitype (BRNM 761731) with strongly supported (99/0.98).