Pycnoporellus Alboluteus
Taxonomy
The species was originally described as Fomes alboluteus by Job Bicknell Ellis and Benjamin Matlack Everhart in 1895. Collected by botanist Charles Spencer Crandall, the type specimens were found growing on the charred trunks of Abies subalpina in the mountains of Colorado, at an elevation of 10,000 feet (3,000 m). In its taxonomic history, it has been transferred to several genera. The original authors moved it to Polyporus in 1898, considering it allied to Polyporus leucospongia. They also noted that the pores developed teeth-like elongations like those of genus Irpex. Other generic transfers include Scindalma by Otto Kuntze in the same year, Aurantiporellus by William Alphonso Murrill in 1895, Aurantiporus by Murrill in 1905, Phaeolus by Albert Pilát in 1937, and Hapalopilus by Appollinaris Semenovich Bondartsev and Rolf Singer in 1943. It was given its current name in 1963 when Czech mycologists František Kotlaba and Zdeněk Pouzar placed it in Pycnoporellus.
The generic name Pycnoporellus is Ancient Greek for "with countless pores". The specific epithet alboluteus is a combination of the Latin words for "white" and "yellow". Curtis Gates Lloyd did not approve of the name, opining: "I hardly see how Ellis could have given it a worse name if he had tried, for it is neither "white" nor "yellow", but orange as Ellis described it. The young growth may possibly be white, but not when developed." The fungus is commonly known as the "orange sponge polypore".
Description
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The fruit bodies of P. alboluteus are annual, and are resupinate; they can be spread out on the substrate surface for up to 1 m (3+1⁄4 ft). Fresh fruit bodies are bright orange, finely grooved, and have a soft and spongy upper surface. The pore surface is orange with angular pores that are usually larger than 1 mm in diameter. It features thin partitions that split to form a teeth-like layer. The flesh is soft and pale orange, up to 2 mm thick, with a felt-like texture. The tubes are the same color as the pores, and continuous with the flesh, measuring up to 2 cm (3⁄4 in) thick. Bruised pores sometimes turn black. All tissues of the fungus turn bright red if a drop of dilute potassium hydroxide is applied. Fresh fruit bodies retain considerable moisture and can be squeezed of liquid like a sponge. The fruit body can be readily removed in large sheets from the wood it grows on. The edibility of the fruit body is unknown. It has a fragrant odor.
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In deposit, the spores are white. The spores are cylindrical, smooth, hyaline (translucent), inamyloid, and measure 9–12 by 3–3.5 μm. Pycnoporellus alboluteus has a monomitic hyphal system, meaning it is made of generative hyphae, which are thin-walled, branched, and narrow. Hyphae in the flesh layer are thin- to thick-walled, frequently branched, and measure 2–10 μm in diameter, while those of the pores are roughly similar in morphology, but measure 3–5 μm. Both forms have a thin incrustation on their walls that gives them a rough appearance when viewed with a light microscope. The hymenium (spore-bearing tissue layer) is 40–60 μm thick, and has abundant cystidia, which are hyaline, and measure 7–9 μm in diameter. They are cylindrical, thin-walled to moderately thick-walled, hyaline, have a septum at the base, and measure 60–120 by 5–10 μm. The basidia (spore-bearing cells) are club-shaped, four-spored, and have dimensions of 25–35 by 6–7 μm.