Auricularia americana

Auricularia americana is a species of fungus in the family Auriculariaceae found in North America and East Asia. Its basidiocarps (fruitbodies) are gelatinous, ear-like, and grow on dead conifer wood.

Taxonomy
The species was originally described in 1987 from Quebec on Abies balsamea, but was not validly published until 2003. Molecular research, based on cladistic analysis of DNA sequences, has shown that Auricularia americana is a distinct species.

The species was formerly confused with Auricularia auricula-judae, which grows on broadleaf wood and is confined to Europe.

Description
Auricularia americana forms thin, brown, rubbery-gelatinous fruit bodies that are ear-shaped and 2.5-10 cm across and about 3 mm thick. The fruitbodies occur singly or in clusters. The upper surface is finely pilose. The spore-bearing underside is smooth. The spore print is white.

Microscopic characters
The microscopic characters are typical of the genus Auricularia. The basidia are tubular, laterally septate, 55–70 × 4–5 μm. The spores are allantoid (sausage-shaped), 14–16.5 × 4.5–5.5 μm.

Similar species
In North America, Auricularia angiospermarum is almost identical but grows on the wood of broadleaf trees. No other North American Auricularia species grows on conifer wood. In China and Tibet, however, a second species, A. tibetica, also occurs on conifers. It can be distinguished microscopically by its longer basidia and larger basidiospores.

Additionally, A. nigricans, Exidia crenata, and Phylloscypha phyllogena are similar.

Habitat and distribution
Auricularia americana is a wood-rotting species, typically found on dead attached or fallen wood of conifers. It is widely distributed in North America (primarily in the Northeast, between April and September) and is also known from China and the Russian Far East.