Pluteus brunneodiscus Z.X. QI, B. Zhang & Y. Li, 2024

Qi, Zheng-Xiang, Qian, Ke-Qing, Yue, Lei, Wang, Li-Bo, Guo, Di-Zhe, Wu, Dong-Mei, Gao, Neng, Zhang, Bo & Li, Yu, 2024, New species, new records and common species of Pluteus sect. Celluloderma from northern China, MycoKeys 104, pp. 91-112 : 91

Pluteus brunneodiscus Z.X. QI, B. Zhang & Y. Li sp. nov.

Figs 2A-B , 3

Typification.

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!).

Sequences holotype.

ITS: PP002167, TEF1-α: PP062823.

Etymology.

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

Diagnosis.

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.

Description.

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.

Ecology and distribution.

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.

Additional specimens examined.

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) .

Notes.

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 Pluteus 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 .

Figures

Figure 2. Basidiomata features A-B Pluteus brunneodiscus C-D P. cystidiosus E-F P. chrysophlebius G-I P. romellii. Photos by Zheng-xiang Qi (A-B, G-I). Photos by Di-zhe Guo (C-F). Scale bars: 1 cm.

Figure 3. A Macroscopic characteristics of Pluteus brunneodiscus B basidiospores C pleurocystidia D basidia E pileipellis terminal cells F cheilocystidia. Scale bars: 1 cm (A); 10 µm (B-F).