Phylloporus aurantiacus Halling & Mueller in Halling et al., Mycotaxon 73: 64. 1999.
Pileus 1–3 cm broad, at first plane, with age depressed, dry; disc even, at first orange, then orange; margin even, when young orange to yellow orange, then yellow orange; surface matted tomentose to tomentose, becoming matted subtomentose; maculose color spots absent or present (sometimes), yellow; with NH4 no reaction (same reaction in pileus flesh). Flesh 2–5 mm thick, yellow, staining absent; odor mild; taste mild. Hymenophore lamellate, decurrent. Lamellae 1–3 mm wide, close, not anastamosing, rarely somewhat intervenose, when young orange to orange brown, with age orange to orange brown, staining green; edges even. Stipe 3–5 cm long, 4–5 mm wide, equal, strict, not radicating, dry; upper half when young floccose to fibrillose, red to orange (with yellow undertones), with age floccose to fibrillose, red to orange (with yellow undertones); lower half when young floccose to fibrillose, red to orange (with yellow undertones), with age floccose to fibrillose, red to orange (with yellow undertones); base yellow, staining not present or green. Stipe interior solid; flesh above when young yellow, with age yellow, staining not present; flesh at base when young yellow, with age yellow, staining not present. Basal mycelium bright yellow.
Basidiospores 5.6–7.7 µm long, 3.5–5 µm wide, mean Q = 1.6, smooth, ovoid to subellipsoid, weakly dextrinoid, with KOH straw yellow. Basidia 35–42 µm long, 8–10.5 µm wide, cylindric to clavate, hyaline, 4 -sterigmate. Hymenial cystidia 60–90 µm long, 7–10 µm wide, more common on sides of lamellae, thin walled, hyaline, subfusoid to subcylindrical, gelatinization absent, encrusting pigment absent. Hymenophoral trama hyphae bilateral (phylloporoid), 2–6 µm wide, yellow brown in the central stratum, inamyloid. Pileipellis hyphae a trichodermium (tangled), in KOH orange to yellow ochraceous, inamyloid; elements 3.5–7 µm wide, cylindric to elongated, smooth, thin walled, granular content absent, not gelatinized. Pileus trama interwoven, hyaline, inamyloid, with elements 3.5–10 µm wide, smooth (but dissolving a bright yellow pigment in KOH), thin walled. Stipitipellis hyphae vertically oriented, parallel, giving rise to clusters of caulocystidia, 35–90 µm long, 7–10 µm wide, clavate to subfusoid, hyaline to orange, with incrusting pigment absent. Stipe trama hyphae parallel, cylindric, hyaline, inamyloid. Clamp connections absent.
Mycorrhizal host: Quercus.
This species seems closest to P. coccineus described by Corner (1970) from Singapore. The yellow basal mycelium as well as the overall colors are similar. The spores of both taxa are ovoid, an uncommon shape in the genus, and both lack clamp connections. However, Corner’s fungus has yellow flesh that is cyanescent, and the spores are larger (7.5–9 × 6.5–7.5 µm). The Costa Rican entity has yellow flesh but doesn’t change to blue green when exposed. There is a water soluble pigment which dissolves and turns microscopic mounts yellow. So far known only from one site in Cartago Province in the northern Talamancas.
Desc0009.
Cite this publication as: Halling, R. E., G. M. Mueller, and M. J. Dallwitz. 1998 onwards. Leccinum and Phylloporus in Costa Rica: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 13 Decmber 2006. http://www.nybg.org/bsci/res/hall/deltaindex.html. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993 onwards, 1998) should also be cited (see References).
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