Phylloporus phaeoxanthus Singer & Gómez, Brenesia 22: 171. 1984.
Pileus 2.5–4 cm broad, at first plano-convex, with age plane, dry; disc even, at first brown, then remaining brown; margin even, when young brown, then remaining brown; surface tomentose; maculose color spots absent; with NH4 blue green or dull lilac (eventually). Flesh 4–10 mm thick, white, staining absent; odor mild; taste mild; with NH4 blue green or dull lilac (eventually). Hymenophore lamellate, decurrent. Lamellae 1–8 mm wide, close, anastamosing to subporoid, when young yellow, with age yellow, staining absent; edges even. Stipe 2–3 cm long, 6–8 mm wide, equal to tapering downwards, curved, dry; upper half when young finely pruinose, pale brown to brown, with age finely pruinose, pale brown to brown; lower half when young finely pruinose, pale brown to brown, with age finely pruinose, pale brown to brown; base pale yellow to yellow, staining not present. Stipe interior solid; flesh above when young white to whitish yellow to yellow, with age white to whitish yellow to yellow, staining not present; flesh at base when young white to yellow, with age white to yellow, staining not present. Basal mycelium yellow.
Basidiospores (6.5–)8.5–12.3(–14) µm long, (3.3–)4.3–4.8 µm wide, mean Q = 2.84, smooth, fusoid, inamyloid, with KOH light brown melleous. Basidia 23–40 µm long, 6–9 µm wide, clavate, hyaline, 4 -sterigmate. Hymenial cystidia 35–90 µm long, 9–20 µm wide, moderately abundant, thin walled, hyaline, ventricose to fusoid to utriform, encrusting pigment present. Hymenophoral trama hyphae bilateral (phylloporoid), up to 15 µm wide, hyaline, in KOH finely melleous ochre encrusted, inamyloid. Pileipellis hyphae a trichodermium and forming a palisade, in KOH yellow, inamyloid; elements 6–12 µm wide, elongated, smooth, thick walled, not gelatinized. Intercalary cells subisodiametric to isodiametric, 10–12 µm long, 8–10 µm wide. Pileus trama interwoven, hyaline, inamyloid. Stipitipellis hyphae vertically oriented, parallel to interwoven, giving rise to clusters of caulocystidia, 15–45 µm long, 7–13 µm wide, ventricose to fusoid, with incrusting pigment sometimes present. Stipe trama hyphae parallel to subparallel, cylindric, hyaline, inamyloid. Clamp connections absent.
Mycorrhizal host: Quercus.
The yellow mycelium at the stipe base, brown pileus, unchanging context, palisadic arrangement of hyphal elements in the piliepellis, and blue ammonia reaction are diagnostic. Variety simplex is a known variant with thin walled, unencrusted hymenial cystidia. The species is also currently known from Colombia and Mexico.
Desc0015.
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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