Black Tooth

Appearance

Fruitbodies of "Phellodon niger" have a cap and a stipe, and so fall into the general class of "stipitate hydnoid fungi". Individual caps are up to 5 cm in diameter, but caps of neighboring fruitbodies often fuse together to create larger compound growths. Caps are flat to depressed to somewhat funnel-shaped, with a felt-like texture at first before developing concentric pits, wrinkles, and ridges. Initially whitish, the cap later darkens in the center to grey, grey-brown, or black. The stipe, measuring up to 4 cm long, is roughly the same color as the cap. On the underside of the caps are grey spines, up to 4 mm long. The outer covering of the stipe is a thick felty layer of mycelium that absorbs water like a sponge. In conditions of high humidity, "P. niger" can form striking drops of black liquid on the actively growing caps. The flesh has an odor of fenugreek when it is dry. The mushroom tissue turns bluish-green when tested with a solution of potassium hydroxide.

The ellipsoid, hyaline spores measure 3.5–5 by 3–4 µm. The basidia are club-shaped, four-spored, and measure 25–40 by 5–7 µm. "Phellodon niger" has a monomitic hyphal system, producing generative hyphae with a diameter of 2.5–5 µm.

This fungus is considered inedible.

Distribution

The ectomycorrhizae that "P. niger" forms with Norway spruce has been comprehensively described. It is distinguished from the ectomycorrhizae of other Thelephorales species by the unique shape of its chlamydospores. Stable isotope ratio analysis of the abundance of the stable isotope carbon-13 shows that "P. niger" has a metabolic signature close to that of saprotrophic fungi, indicating that it may be able to obtain carbon from sources other than a tree host.

"Phellodon niger" is found in continental Europe, where it has a widespread distribution, and in North America. In a preliminary assessment for a red list of threatened British fungi, "P. niger" is considered rare. In Switzerland, it is considered a vulnerable species. "Phellodon niger" was included in a Scottish study to develop species-specific PCR primers that can be used to detect the mycelia of stipitate hydnoids in soil. Collections labelled as "P. niger" from the United Kingdom that were DNA tested, revealed additional cryptic species. Analysis using PCR can determine the presence of a "Phellodon" species up to four years after the appearance of fruitbodies, allowing a more accurate determination of their possible decline and threat of extinction.

Habitat

The ectomycorrhizae that "P. niger" forms with Norway spruce has been comprehensively described. It is distinguished from the ectomycorrhizae of other Thelephorales species by the unique shape of its chlamydospores. Stable isotope ratio analysis of the abundance of the stable isotope carbon-13 shows that "P. niger" has a metabolic signature close to that of saprotrophic fungi, indicating that it may be able to obtain carbon from sources other than a tree host.

"Phellodon niger" is found in continental Europe, where it has a widespread distribution, and in North America. In a preliminary assessment for a red list of threatened British fungi, "P. niger" is considered rare. In Switzerland, it is considered a vulnerable species. "Phellodon niger" was included in a Scottish study to develop species-specific PCR primers that can be used to detect the mycelia of stipitate hydnoids in soil. Collections labelled as "P. niger" from the United Kingdom that were DNA tested, revealed additional cryptic species. Analysis using PCR can determine the presence of a "Phellodon" species up to four years after the appearance of fruitbodies, allowing a more accurate determination of their possible decline and threat of extinction.