Caloboletus luolongensis Xing Mo, W. P. Zhang & X. H. Xu 2026, sp. nov.

Caloboletus luolongensis Xing Mo, W. P. Zhang & X. H. Xu sp. nov. Fig. 2 Etymology. Named after the collection site, Luolong Town, Yingzui County, Guizhou Province. Holotype. China • Guizhou Province: Zunyi City, Daozhen Gelaozu Miaozu Autonomous County, Luolong Town, Yingzui County; 29°6'40"N, 107°45'44"E, elev. 1,347 m, 24 September 2025, X. Mo and Z. Q. Qi, M 83 (HKAS 151555). Description. Basidiomata medium-sized. Pileus 6–8 cm in diameter, convex to applanate, margin enrolled slightly; surface dry, pale yellow (1 B 4-6), at first rugulose especially near the margin, then subrugulose with age, finely tomentose to tomentose, unchanging in color when bruised. Context 1.3–1.7 cm thick, pale yellow (1 B 2-3), the lower part turning light blue quickly when injured. Hymenophore poroid, adnate or slightly depressed around apex of stipe. Pores angular, 1–2 mm in diameter, densely arranged, yellowish-white (30 A 2) to yellowish-brown (4 A 4), changing blue quickly when injured; tubes 4–6 mm in length, turning blue quickly when bruised. Stipe 8–9 × 1–2 cm, subcylindric, solid; surface dry, apical part bright yellow (2 A 5–2 B 5), transitioning to rose-red (12 C 5-6) towards the middle, and yellow at the base, covered with concolorous, longitudinal reticulation, changing bluish when injured; context yellowish to yellow, changing blue quickly when injured; basal mycelium white. Odor not distinctive. Taste not recorded. Basidiospores (11.04 –) 11.9–14.91 (– 15.77) × (4.41 –) 5.03–6.52 (– 7.14) μm [Q = (1.88 –) 2.06–3.07 (– 3.25) μm, Qm = 2.45 ± 0.30 μm], narrowly ellipsoid to subcylindrical with a slight suprahilar depression, colorless to pale yellow. Basidia 42–54 × 10–15 μm, clavate, thin-walled, four-spored, sterigmata 2–4 μm in length, colorless to yellowish in KOH. Hymenophoral trama boletoid. Cheilocystidia 37–53 × 6–10 μm, lageniform, thin-walled, colorless to pale yellow in KOH. Pleurocystidia 55–85 × 7–12 μm, fusiform to lanceolate, thin-walled, colorless to yellowish in KOH. Pileipellis composed of interwoven hyphae, 4–8 μm wide, and consistently encrusted with brown extracellular pigment. Stipitipellis consists of pale yellow, parallel hyphae, 7–15 μm wide. All hyphae show no reaction in Melzer’s reagent. Clamp connections absent in all tissues. Habitat. Solitary or scattered in mixed forests of Fagaceae (Quercus spp., Castanopsis spp.) and Pinaceae (P. massoniana). Distribution. China, Guizhou Province. Additional material examined. China • Guizhou Province: Zunyi City, Daozhen Gelaozu Miaozu Autonomous County, Luolong Town, Yingzui County; 29°6'40"N, 107°45'44"E, elev. 1347 m, 24 September 2025, X. Mo and Z. Q. Qi, M 77 (HKAS 151556). Notes. Caloboletus luolongensis is characterized by a rugose pileus with a slightly incurved margin, a longitudinally reticulate stipe that is rose-red over its middle and lower parts, and a context that bruises blue when injured. Morphologically, C. luolongensis is highly similar to C. panniformis (Taneyama & Har. Takah.) Vizzini and C. polygonius (A. E. Hills & Vassiliades) Vizzini. However, C. panniformis exhibits a reticulate surface on the upper half that becomes pruinose downward, with a reddish-brown (9 D 5) tint toward the base, and the reticulation and pruina appear dull (Takahashi et al. 2013; Chai et al. 2019); C. polygonius is characterized by a dry pileus that cracks into polygonal scales at maturity and a yellow stipe covered with dense reddish fibrils but lacking reticulation (only a faint reticulum occasionally at the stipe apex) (Hills and Vassiliades 1999). Among other species of Caloboletus, C. taienus and C. xiangtoushanensis exhibit pores ranging from deep red and brownish-red to ruby (10 C 8–12 C 8) and deep orange to reddish-orange, respectively (Zhang et al. 2017). The cap of Caloboletus griseoflavus is grayish-white to grayish-brown, and the stem is yellow (Mao et al. 2023). C. radicans has large basidiomata (pileus 8–30 cm in diameter) and a root-like base extending into the soil (Bon et al. 1987). The base of the stipe of Caloboletus marshii is often bulbous, and its surface is completely devoid of reticulation. C. inedulis has conspicuous red reticulation on the surface of the stipe and a cap that commonly cracks with age (Zhao et al. 2014 a).