Phyllotopsis nidulans


Phyllotopsis nidulans, commonly known as the mock oyster or the orange oyster, is a species of fungus in the family Phyllotopsidaceae.
The fungus fruit body consists of a fan-shaped, light orange fuzzy cap up to wide that grows singly or in overlapping clusters. On the cap underside are crowded orange gills. Mock oyster mushrooms have an unpleasant odor and are regarded as inedible.
It is widely dispersed in temperate zones of the Northern Hemisphere, where it grows on decaying wood.

Taxonomy

The mock oyster was first described scientifically in 1798 by Christian Hendrik Persoon as Agaricus nidulans. The specific epithet nidulans means "partly encased or lying in a cavity". It is commonly known as "nestcap". It is the type species of the genus Phyllotopsis.

Description

The caps are wide. The stems are either very short or nonexistent. The flesh has a thiol-like odor similar to rotten cabbage or rotten eggs.
The spore print is pink to tannish. The smooth, sausage-shaped to cylindrical basidiospores measure 5–7 μm long by 2–3 μm wide. Clamp connections are present in the hyphae.

Chemistry

The predominant pigments in the fruit bodies include beta-carotene, alpha-carotene, echinenone, and astaxanthin. P. nidulans also produces a unique amino acid, 3- l-alanine.

Similar species

Phyllotopsis subnidulans, found in the eastern United States, is similar in appearance. It can be distinguished by a deeper orange color, thinner gills with wider inter-gill spacing, and curved to sausage-shaped spores. Other similar species include Lentinellus ursinusus, Crepidotus mollis, Panus rudis, Panus conchatus, and Pleurotus ostreatus.

Habitat and distribution

Fruit bodies grow singly or in overlapping clusters on dead wood. Phyllotopsis nidulans is widely distributed in temperate regions of the Northern Hemisphere. Its range extends north to Alaska, and includes Costa Rica, where it has been recorded in the Talamanca mountains and on the Poas Volcano. In Asia, it has been recorded in Korea.

Edibility

Although not known to be poisonous, the disagreeable odor would deter most from eating the mushrooms.