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

Figs 2 j – l , 7

Etymology.

Latin “ roseus ”, referring to pinkinsh to dark reddish pileus.

Holotype.

China • Hainan Province, Wuzhishan County, Wuzhishan of Hainan Tropical Rainforest National Park , alt. 600 m, 18.9°N, 109.5°E, 8 May 2024, N. K. Zeng 8516 ( FHMU 7888 ) .

Diagnosis.

Differs from closest species of Chalciporus by a pinkish to dark reddish pileus with squamules, a yellow hymenophore bruising blue, a pale yellow context changing blue when bruised, broadly ellipsoid to elongate basidiospores measuring 4–5.5 × 3–3.5 μm, and a trichodermal pileipellis.

Description.

Basidiomata small-sized. Pileus 2.8–4.1 cm in diameter, hemispherical to applanate; surface dry, pinkish to dark reddish (11 A 4–11 B 5), covered with squamules; context 0.3–0.7 cm in thickness in the center of the pileus, pale yellow (1 A 2), changing blue when bruised. Hymenophore poroid, slightly decurrent; pores subangular to roundish, 0.1–0.25 cm wide, yellow (1 A 4), changing blue in color when bruised; tubes yellowish, changing blue when bruised. Stipe 4.7–6.2 × 0.4–0.8 cm, central, solid, subcylindrical; surface pinkish to dark reddish (11 A 4–11 B 5), with distinctly longitudinal striations; context pale yellow (1 A 2), changing red when bruised; basal mycelium white. Odor indistinct. Taste mild.

Basidiospores [60 / 3 / 3] (3.5) 4–5.5 (6) × (2.5) 3–3.5 (4) μm, Q = (1.14) 1.17–1.83 (2.0), Q m = 1.54 ± 0.18, yellowish brown in KOH, broadly ellipsoid, ellipsoid to elongate, slightly thick-walled (0.8–1 µm), smooth under the light microscope. Basidia 7–22 × 4–8 μm, clavate, thin-walled, 4 - spored, colorless to pale yellow in KOH; sterigmata 2–6 μm in length. Cheilocystidia 26–44 × 5–9 μm, fusiform or subfusiform, slightly thick-walled (up to 1 μm), colorless to pale yellow in KOH. Pleurocystidia 19–43 × 5–8 μm, fusiform or subfusiform, thin-walled, colorless to pale yellow in KOH. Hymenophoral trama boletoid, colorless to yellowish in KOH, thin- to slightly thick-walled (up to 0.5 μm), 9–15 μm wide. Pileipellis a trichoderm 150–250 μm in thickness, composed of colorless to pale yellow in KOH, slightly thick-walled (up to 1 μm) hyphae; terminal cells 14–40 × 6–10 μm, clavate to subcylindrical or cystidioid. Pileus trama made up of hyphae 5–19 μm in diameter, slightly thick-walled (up to 1 μm), colorless in KOH. Stipitipellis a trichoderm-like structure 700–800 μm thick, composed of hyaline to pale yellow in KOH, thin-walled hyphae; terminal cells 10–29 × 4.5–9 μm, clavate or subcylindrical. Stipe trama composed of parallel hyphae 3–7 μm 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).

Additional materials examined.

China • Hainan Province: Wuzhishan County, Wuzhishan of Hainan Tropical Rainforest National Park , alt. 600 m, 18.9°N, 109.5°E, 8 May 2024, N. K. Zeng 8516-1 ( FHMU 11614 ) ; • same location and date, N. K. Zeng 8516-2 ( FHMU 11615 ) .

Notes.

Phylogenetically, C. roseus is closely related to lineage 5, which includes two collections from southwestern China (Fig. 1 ). However, since both specimens representing this lineage are immature, detailed morphological comparisons will be performed in future studies when mature specimens become available. Morphologically, the feature of the dark reddish pileus and yellow hymenophoral surface of C. roseus distinguishes it from other species in the genus Chalciporus .

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 7. Microscopic features of Chalciporus roseus (FHMU 7888, holotype). a. Basidia; b. Basidiospores; c. Cheilocystidia; d. Pleurocystidia; e. Pileipellis; f Stipitipellis. Scale bars: 10 µm. Drawings by X. N. Li.