Chalciporus brunneus N. K. Zeng & X. Zhang, 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

Chalciporus brunneus N. K. Zeng & X. Zhang sp. nov.

Figs 2 f – h , 5

Etymology.

Latin “ brunneus ”, referring to the pale brown to brown pileus.

Holotype.

China • Hainan Province, Changjiang County, Bawangling of Hainan Tropical Rainforest National Park , alt. 650 m, 19.2°N, 109.1°E, 13 May 2025, N. K. Zeng 8522 ( FHMU 8246 ) .

Diagnosis.

Differs from closest species of Chalciporus by a pale brown to brown pileus, a yellowish-white context unchanging when bruised, a yellow hymenophore, a stipe usually reddish at the apex, and an intricate trichodermal pileipellis.

Description.

Basidiomata very small to small-sized. Pileus 1.2–3.6 cm in diameter, subhemispherical to convex or plano-convex, margin incurved; surface slightly viscid when wet, pale brown to brown (6 C 2–6 C 3); context 0.2–0.7 cm in thickness in the center of the pileus, yellowish white (1 A 2), unchanging in color when bruised. Hymenophore poroid, slightly decurrent; pores roundish or angular, 0.15–0.25 cm wide, yellow (5 A 4), unchanging in color when bruised; tubes approximately 0.3 cm long, yellowish orange (5 A 5), unchanging in color when bruised. Stipe 1.8–3.8 × 0.3–0.65 cm, central, solid, subcylindrical; surface smooth, usually reddish at the apex, yellowish white (1 A 2) in the upper part, gradually becoming brown (6 B 2) toward the base, with distinct reddish longitudinal striations; context yellowish white (1 A 2), unchanging in color when bruised; basal mycelium white. Odor indistinct. Taste mild.

Basidiospores [160 / 8 / 4] (7) 8–10.5 (11) × 3–5 μm, Q = (1.70) 1.90–3.00 (3.33), Q m = 2.34 ± 0.31, yellowish brown in KOH, elongated to cylindrical, slightly thick-walled (0.8–1 µm), smooth under the light microscope. Basidia 19–30 × 6–9 μm, clavate, slightly thick-walled (up to 1 µm), 4 - spored, colorless to pale yellow in KOH; sterigmata 2–4 μm in length. Cheilocystidia 33–65 × 5–11 μm, fusiform or subfusiform, slightly thick-walled (up to 1 µm), colorless in KOH. Pleurocystidia 33–71 × 6–9 μm, fusiform or subfusiform, slightly thick-walled (up to 1 µm), colorless in KOH. Hymenophoral trama boletoid, colorless to yellowish in KOH, thin- to slightly thick-walled (up to 0.5 μm), 4–10 μm wide. Pileipellis an intricate trichoderm 200–360 μm in thickness, composed of hyaline in KOH, slightly thick-walled (up to 1 µm) hyphae; terminal cells 8–69 × 4–8 μm, clavate to subcylindrical or cystidioid. Pileus trama made up of hyphae 4–20 μm in diameter, slightly thick-walled (up to 1 µm), colorless in KOH. Stipitipellis a trichoderm-like structure 150–300 μm thick, composed of hyaline to pale yellow in KOH, slightly thick-walled (up to 1 µm) hyphae; terminal cells 30–60 × 5–6 μm, clavate or subcylindrical, occasionally subfusiform. Stipe trama composed of parallel hyphae 3–13 μm in diameter, cylindrical, thin- to slightly thick-walled (up to 1 μm), hyaline to pale yellow in KOH. Clamp connections absent in all tissues.

Habitat.

Gregarious on the ground in forests dominated by fagaceous trees ( Lithocarpus spp. ).

Known distribution.

Southern China ( Hainan Province).

Additional materials examined.

China • Hainan Province, Changjiang County, Bawangling of Hainan Tropical Rainforest National Park , alt. 650 m, 19.2°N, 109.1°E, 12 May 2025, N. K. Zeng 8522-1 ( FHMU 11617 ) ; • same location and date, N. K. Zeng 8522-2 ( FHMU 11547 ) ; • same location and date, N. K. Zeng 8522-3 ( FHMU 11548 ) .

Notes.

Chalciporus brunneus is phylogenetically related to C. aurantiolepidotus and C. hainanensis . However, C. hainanensis has a light orange-brown pileus, a white context turning red when bruised, and a reddish-orange hymenophore (see below). The morphological differences between C. brunneus and C. aurantiolepidotus have been discussed above. Morphologically, C. brunneus is similar to C. sinensis . However, C. sinensis has a pileus covered with brown to grey-brown scales, shorter, subglobose to ellipsoid basidiospores measuring 4–7 × 3.5–5 μm, and a trichodermial pileipellis ( Xu et al. 2021).

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 5. Microscopic features of Chalciporus brunneus (FHMU 8246, holotype). a. Basidia; b. Basidiospores; c. Cheilocystidia; d. Pleurocystidia; e. Pileipellis; f. Stipitipellis. Scale bars: 10 µm. Drawings by X. N. Li.