Crocinoboletus rufoaureus

Crocinoboletus rufoaureus (Massee) N.K. Zeng, Zhu L. Yang & G. Wu, in Zeng et al., Phytotaxa 175(3): 134 (2014)

Pileus 4–8 cm in diameter, subhemispherical when young, then convex to applanate; surface dry, yellowish orange, bright orange to reddish orange, covered with minute, reddish brown squamules, turning bluish olivaceous quickly, then blackening when bruised; margin incurved; context 0.9–1.4 cm in thickness in the center of the pileus, vivid golden yellow, turning bluish olivaceous quickly when bruised. Hymenophore poroid, adnate or slightly depressed around apex of stipe; pores subcircular, minute, 0.2–0.5 mm in diameter, orange, turning bluish olivaceous quickly, then blackening when bruised; tubes 3–5 mm in depth, orange, turning bluish olivaceous quickly, then blackening when bruised. Stipe 5–8 × 1–3 cm, centrally attached, subcylindric, solid; surface dry, concolorous with the pileus, covered with minute, reddish orange squamules, sometimes ribbed by the fine anastomosing longitudinal rugulae, turning bluish olivaceous quickly, then blackening when bruised; context vivid golden yellow, turning bluish olivaceous quickly when bruised; annulus absent. Basal mycelium orangish yellow. Odor not distinct. Taste not distinct.

Basidia 23–34 × 7–10 μm, clavate, thin-walled, 4-spored, colorless to yellowish in KOH; sterigmata 5–6 μm in length. Basidiospores [160/8/2] (9–)11–14(–15) × 4–5(–5.5) μm, Q = (1.80–)2.20–3.25(–3.75), Qm = 2.65 ± 0.38, subfusiform to ellipsoid, slightly thick-walled (up to 0.5 μm), olive brown to yellowish brown in KOH, smooth, inamyloid. Hymenophoral trama subboletoid with weakly gelatinous lateral strata. Cheilocystidia 27–42 × 6–9 μm, abundant, subfusiform or fusiform, thin-walled, colorless, brownish yellow to yellowish brown in KOH, no encrustations. Pleurocystidia 28–41 × 5.5–9 μm, abundant, fusiform or subfusiform, thin-walled, colorless, brownish yellow to yellowish brown in KOH, no encrustations. Pileipellis an interwoven trichoderm at the middle part of the pileus and a cutis at the margin of the pileus; composed of thin-walled hyphae 3–7 μm wide, occasionally branched, with terminal cells 24–50 × 5–6 μm, narrowly clavate or subcylindrical, with obtuse apex; yellowish to yellowish brown in KOH. Pileal trama composed of thin-walled hyphae 3–7 μm in diameter, colorless to yellowish in KOH. Stipitipellis a trichoderm-like structure composed of thin- to slightly thick-walled (up to 0.5 μm) hyphae 3–14 wide, with narrowly or broadly clavate, occasionally subfusiform terminal cells measuring 15–30 × 9–14 μm, yellowish to yellowish brown in KOH. Stipe trama composed of cylindrical, parallel hyphae, 4–10 μm wide, thin- to slightly thickwalled (up to 1 μm), colorless to yellowish in KOH. Clamp connections absent in all tissues.

Habitat and habitat: Solitary, scattered to gregarious on the ground in broadleaf forests dominated by Fagaceae.

Known distribution: Singapore, Malaysia (Corner 1972, 1974; Horak 2011), subtropical and tropical region of China. Possibly Indonesia, Papua New Guinea (type of Boletus flammeus) (Heim 1966; Corner 1972; Horak 2011).

Index Fungorum number: IF 809229