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

Figs 2 c – e , 4

Etymology.

Latin “ aurantiolepidotus ”, referring to the orange squamules on the pileal surface.

Holotype.

China • Hainan Province, Changjiang County, Bawangling of Hainan Tropical Rainforest National Park , alt. 650 m, 19.1°N, 109.2°E, 8 May 2022, N. K. Zeng 7075 ( FHMU 7049 ) .

Diagnosis.

Differs from closest species of Chalciporus by a very small basidioma, a dry pileus covered with orange to reddish squamules, a reddish-orange to reddish hymenophore, and a trichodermal pileipellis.

Description.

Basidiomata very small-sized. Pileus 2–2.5 cm in diameter, subhemispherical to convex when young, plano-convex to applanate when mature, margin occasionally upturned; surface dry, covered with orange (6 B 4) to reddish (6 B 3) squamules; context 0.2–0.3 cm in thickness in the center of the pileus, white (1 A 1), unchanging in color when bruised. Hymenophore poroid, slightly decurrent; pores angular, 0.1–0.25 cm wide, reddish-orange (7 A 4) to reddish (8 A 5), unchanging in color when bruised; tubes 0.2–0.3 cm long, reddish (8 A 5), unchanging in color when bruised. Stipe 1.6–1.7 × 0.3 cm, central, solid, subcylindrical; surface pale brown, with distinctly longitudinal striations; context white (1 A 1), unchanging in color when bruised; basal mycelium white. Odor indistinct. Taste mild.

Basidiospores [60 / 8 / 3] (8) 8.5–11 (12) × 4–5 μm, Q = (1.6) 1.7–2.5 (3.0), Q m = 2.22 ± 0.28, yellowish-brown in KOH, elongated to cylindrical, slightly thick-walled (0.8–1 µm), smooth under the light microscope. Basidia 18–30 × 8–12 μm, clavate, slightly thick-walled (up to 1 µm), 4 - spored, colorless to pale yellow in KOH; sterigmata 2–5.5 μm in length. Cheilocystidia 38–63 × 8–12 μm, fusiform or subfusiform, slightly thick-walled (up to 1 μm), colorless to pale yellow in KOH. Pleurocystidia 41–61 × 9–13 μm, fusiform or subfusiform, slightly thick-walled (up to 1 μm), pale yellow in KOH. Hymenophoral trama boletoid, colorless to yellowish in KOH, thin- to slightly thick-walled (up to 0.5 μm), 5–10 μm wide. Pileipellis a trichoderm 250–300 μm in thickness, composed of pale yellow in KOH, slightly thick-walled (up to 1 μm) hyphae; terminal cells 20–61 × 5–9 μm, clavate to subcylindrical or cystidioid. Pileus trama made up of hyphae 5–19 μm in diameter, thick-walled (up to 1.5 μm), yellow in KOH. Stipitipellis a trichoderm-like structure 150–200 μm thick, composed of hyaline to pale yellow in KOH, thin-walled hyphae; terminal cells 15–30 × 4–7 μm, clavate or subcylindrical, occasionally subfusiform. Stipe trama composed of parallel hyphae 3–7 μm in diameter, cylindrical, thin-walled, yellow in KOH. Clamp connections absent in all tissues.

Habitat.

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

Known distribution.

Southern China ( Hainan Province), probably Guangdong Province, and Thailand (Fig. 1 ).

Additional materials examined.

China • Hainan Province: Changjiang County, Bawangling of Hainan Tropical Rainforest National Park , alt. 650 m, 19.1°N, 109.2°E, 18 May 2022, N. K. Zeng 7076 ( FHMU 7056 ; ZJMR 330727230331 ) ; • Baisha County, Yinggeling of Hainan Tropical Rainforest National Park , alt. 650 m, 19.2°N, 109.5°E, 20 July 2022, N. K. Zeng 7352 ( FHMU 7472 ) .

Notes.

Chalciporus aurantiolepidotus is phylogenetically related and morphologically similar to C. brunneus , C. hainanensis Ming Zhang & T. H. Li , and C. vulparius . However, C. brunneus has a pale brown to brown pileus, a yellow hymenophore, a stipe usually reddish at the apex, and an intricate trichodermal pileipellis (see below); C. hainanensis has a light orange-brown pileus, a white context changing red when bruised, and a stipe usually reddish at the apex (see below); C. vulparius has a tomentose, reddish-brown to pale reddish-brown pileus, a reddish-pink hymenophore, a stipe covered with white to brown scales, and shorter basidiospores measuring 5.5–9 × 3–5 μm ( Xu et al. 2021).

Figures

Figure 1. Phylogram of Chalciporoideae inferred from multilocus (rDNA 28 S, ITS, TEF 1, and RPB 2) dataset using RAxML. RAxML bootstrap percentages (BS ≥ 70 %) and Bayesian posterior probabilities (PP ≥ 0.95) are indicated above or below the branches as BS / PP. Note. SE = southeastern China; SW = southwestern China; NE = northeastern China.

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 4. Microscopic features of Chalciporus aurantiolepidotus (FHMU 7049, holotype). a. Basidia; b. Basidiospores; c. Cheilocystidia; d. Pleurocystidia; e. Pileipellis; f. Stipitipellis. Scale bars: 10 µm. Drawings by X. N. Li.