Amauroderma

Amauroderma is a genus of polypore fungi in the family Ganodermataceae. The genus, widespread in tropical areas, contains about 70 species. "Amauroderma" fungi are wood-decay fungi that feed and fruit on decayed branches and trunks.
The fruit bodies of "Amauroderma" fungi comprise a cap and a stipe, and are typically woody, leathery, or corky in texture. The spores produced are usually spherical or nearly so, with a characteristic double wall structure that features U-shaped thickenings.
Taxonomy.
"Amauroderma" was circumscribed by American mycologist William Alphonso Murrill in 1905. He set "Amauroderma regulicolor" (previously known as "Fomes regulicolor" Berk. ex Cooke), collected from Cuba, as the type species. The name "Amauroderma" had been used previously by Narcisse Patouillard, when he proposed that "Ganoderma" be divided into the sections "Ganoderma" and "Amauroderma". Patouillard described the characteristics of section "Amauroderma" as follows: "Spores globose or subglobose, devoid of truncated base, warty, woodruff or smooth; crust hat or dull stipe pruinose, rarely shining." In 1920, Torrend promoted "Ganoderma" sect. "Amauroderma" to generic status, with "Amauroderma auriscalpium" as the type. This resulted in an illegitimate homonym, as Murrill's earlier usage of the name has priority.
The generic name means "dark/dusky-skinned" (from , meaning "dark or dusky", and , meaning "skin").
Several studies using molecular phylogenetics have shown that "Amauroderma", as currently circumscribed, is not a monophyletic taxon and will need to be revised.
Description.
The fruit bodies of "Amauroderma" species are stipitate except in "A. andina" and may attain various shapes although centrally stipitate basidiocarps are most common. Several stipes may arise from the same base, frequently resulting in fused caps and compound fruit bodies. In section some fruit bodies are distinct with one or two distinct inner black bands or zones. The stipe is often duplex with an outer dense layer surrounding an inner softer or hollow core sometimes separated by a black band. In species with a distinct tomentum on the stipe, there is often a dark zone just below the tomentum of the cap. These zones are absent from some species with a pale stipe without a tomentum. However, when present they continue into the context and frequently there is also another zone stretching more or less horizontally across the context.
Most basidiospores of "Amauroderma" mushrooms have an inner ornamented wall on which there is a hyaline (translucent) epicutis, which is very thin and difficult to see in ordinary microscopic preparations. Mature basidiospores are pale-yellowish. An apiculus (a depressed area where the spore was once attached to the basidium via the sterigma) is often difficult to observe.
Chemistry.
"Amauroderma camerarium" produces the anti-"Trichomonas vaginalis" protein that has been named amaurocine.
Habitat and distribution.
"Amauroderma" is widespread in tropical areas. Twenty species have been recorded from Brazil; six have been confirmed in China. A collection of "Amauroderma sprucei" made in Florida in 2016 was the first recorded time that the genus has been collected in the United States.
"Amauroderma schomburgkii", "A. coltricioides", and "A. calcigenum" are examples of the genus that have been found fruiting on soil. "Amauroderma schomburgkii" is the most common neotropical species.
Species.
The tenth edition of the "Dictionary of the Fungi" (2008) indicated that were about 30 species in the genus. , Index Fungorum accepts 68 species of "Amauroderma".