Pseudophylloporus castaneus N. K. Zeng, X. Zhang & J. B. Pu, 2025

Zhang, Xu, Li, Xin-Ni, Liang, Wei-Qing, Mu, Xiao-Dong, Yu, Ye-Fei, Wu, Xiao-Jun, Chen, Si-Yu, Pu, Jin-Bao & Zeng, Nian-Kai, 2025, The subfamily Chalciporoideae (Boletaceae, Boletales) in China, MycoKeys 124, pp. 123-157 : 123-157

Pseudophylloporus castaneus N. K. Zeng, X. Zhang & J. B. Pu sp. nov.

Figs 2 m – o , 8

Etymology.

Latin “ castaneus ”, referring to the chestnut-brown pileus.

Holotype.

China • Zhejiang Province, Pan’an County, Dapanshan National Nature Reserve , alt. 1003 m, 29.0°N, 120.5°E, 7 July 2023, FC 330727230331 ( ZJMR 330727230331 ) .

Diagnosis.

Differs from closest species of Pseudophylloporus by a chestnut-brown pileus, cystidia with golden or yellowish-brown plasmatic pigments, and an intricate trichodermal pileipellis.

Description.

Basidiomata very small-sized. Pileus 2.5–3 cm in diameter, subhemispherical when young, then subhemispherical to plano-convex; surface dry, tomentose, chestnut-brown (5 E 7–5 E 8); context 0.3–0.6 cm in thickness in the center of the pileus, white (1 A 1), changing bluish when injured. Hymenophore lamellate, free; lamellae 0.1–0.3 cm in height, subdistant, usually forked, brown (5 D 4), turning blue quickly. Stipe 1.7–2.6 × 0.3–0.5 cm, clavate or tapering upwards, solid; surface yellow (4 A 3) to yellowish-brown (4 C 5), with purple-reddish (10 E 3) longitudinal striations; context pale yellow (2 A 2), changing blue slightly when injured; basal mycelium yellowish (2 A 4). Odor indistinct. Taste mild.

Basidiospores [60 / 3 / 3] 8–9.5 (10) × 3–4 (4.5) μm, Q = 2.0–3.0, Q m = 2.44 ± 0.29, yellowish brown in KOH, fusoid to cylindrical, slightly thick-walled (0.8–1 µm), smooth under the light microscope. Basidia 24–34 × 5–8 μm, clavate, slightly thick-walled (0.8–1 µm), 4 - spored, colorless to pale yellow in KOH; sterigmata 2–5 μm in length. Cheilocystidia 43–65 × 10–15 μm, abundant, ventricose, subclavate or subfusiform, slightly thick-walled (up to 1 μm), with golden or yellowish brown plasmatic pigment in KOH. Pleurocystidia 41–65 × 8–15 μm, subclavate or subfusiform, thin- to slightly thick-walled (up to 1 μm), with golden or yellowish brown plasmatic pigment in KOH. Hymenophoral trama boletoid, colorless to yellowish in KOH, thin- to slightly thick-walled (up to 0.5 μm), 4–17 μm wide. Pileipellis an intricate trichoderm 150–350 μm in thickness, composed of light yellow in KOH, slightly thick-walled (up to 1 μm) hyphae; terminal cells 25–95 × 4–9 μm, clavate to subcylindrical or cystidioid. Pileus trama made up of hyphae 4–10 μm in diameter, slightly thick-walled (up to 1 μm), yellow in KOH. Stipitipellis a trichoderm-like structure 30–100 μm thick, composed of pale yellow in KOH, slightly thick-walled (up to 1 μm) hyphae, terminal cells 30–60 × 5–6 μm, subclavate or clavate. Stipe trama composed of parallel hyphae 5–30 μm in diameter, cylindrical, thin- to slightly thick-walled (up to 0.5 μm), pale yellow in KOH. Clamp connections present in all tissues.

Habitat.

Solitary or scattered on the ground in forests dominated by fagaceous trees ( Quercus spp. )

Known distribution.

Eastern China ( Zhejiang Province).

Additional materials examined.

China • Zhejiang Province, Pan’an County, Dapanshan National Nature Reserve , alt. 1003 m, 28.9°N, 120.5°E, 28 June 2023, FC 330727230331-1 ( FHMU 11549 ) ; • same location and date, FC 330727230331-2 ( FHMU 11550 ) .

Notes.

Pseudophylloporus castaneus is phylogenetically related and morphologically similar to P. baishanzuensis . However, P. baishanzuensis has a yellowish-brown to pale brown pileus, a stipe densely covered with pale brown scales, cystidia without golden or yellowish brown plasmatic pigments, and a cutis-type pileipellis ( Qin et al. 2024).

Figures

Figure 2. Basidiomata of fungi in the subfamily Chalciporoideae a, b. Buchwaldoboletus lignicola (FHMU 5579); c – e. Chalciporus aurantiolepidotus (c, e FHMU 7049, holotype; d FHMU 7472); f – h. C. brunneus (FHMU 8246, holotype); i. C. hainanensis (FHMU 9951); j – l. C. roseus (FHMU 7888, holotype); m – o. Pseudophylloporus castaneus (ZJMR 330727230331, holotype). Scale bars: 1 cm. a – l. photos by N. K. Zeng; m – o. photos by J. B. Pu.

Figure 8. Microscopic features of Pseudophylloporus castaneus (ZJMR 330727230331, holotype). a. Basidia; b. Basidiospores; c. Cheilocystidia; d. Pleurocystidia; e. Pileipellis; f. Stipitipellis. Scale bars: 10 µm. Drawings by X. N. Li.