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: IF809229
Figure 1. Basidiomata of Crocinoboletus rufoaureus a–g. [a from HKAS 82334; b, e from HKAS 82333; c, e from HKAS 59821; d, f, g from HKAS 82335 (f showing the surface of the pileus turning bluish olivaceous, then blackening when bruised; g showing the surface of the stipe turning bluish olivaceous, then blackening when bruised)].
Figure 2. Microscopic features of Crocinoboletus rufoaureus (a, c from HKAS 82333; b from HKAS 82333 and 82335; d–f from HKAS 82335. drawn by N.K. Zeng). a. Basidia and pleurocystidia. b. Basidiospores. c. Cheilocystidia. d. Pleurocystidia. e. Pileipellis (from the middle part of the pileus). f. Pileipellis (from the marginal part of the pileus). Scale bars = 10 μm.
Key reference:
Zeng N.K., Wu G., Li Y.-C & Liang Z..Q., Yang Z. 2014 Crocinoboletus, a new genus of Boletaceae (Boletales) with unusual boletocrocin polyene pigments. Phytotaxa. 175. 133-140. 10.11646/phytotaxa.175.3.2
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