Auricularia nigricans

Auricularia nigricans is a species of fungus in the family Auriculariaceae. Basidiocarps (fruitbodies} are gelatinous, ear-like, and grow on dead wood of broadleaf trees. It is found in southern and eastern Asia, North America, South America and the Caribbean. Asian examples were formerly considered as a separate species described as Auricularia polytricha.

Taxonomy
The species was first described in 1788 as Peziza nigrescens by the Swedish botanist Olof Swartz, based on a collection he made from Jamaica. In a later publication he changed the name to Peziza nigricans, which was accepted by the Swedish mycologist Elias Magnus Fries. For abstruse nomenclatural reasons, Fries's sanctioned name takes priority over Swartz's original name. In his monograph of Auricularia species, American mycologist Bernard Lowy rejected the name as being "doubtful", preferring to call the species Auricularia polytricha. Olof Swartz's original collection still exists, however, enabling the identity of his species to be confirmed. Molecular research, based on cladistic analysis of DNA sequences, has shown that Auricularia nigricans is distinct.

Description
Auricularia nigricans forms thin, rubbery-gelatinous fruit bodies that are ear-shaped and up to 60 mm across and 4 mm thick. The fruitbodies occur singly or in clusters. The upper surface is densely tomentose and ash-grey to yellowish brown. The spore-bearing underside is smooth and pinkish to brown.

Microscopic characters
The microscopic characters are typical of the genus Auricularia. The basidia are tubular, laterally septate, 50–75 × 3-6.5 μm. The spores are allantoid (sausage-shaped), 14.5–17 × 5–7 μm. The surface hairs are 650–1080 μm long.

Similar species
Auricularia cornea is similar but has much shorter surface hairs 200–400 μm long.

Habitat and distribution
Auricularia nigricans is a wood-rotting species, typically found on dead attached or fallen wood of broadleaf trees. It is widely distributed in the Americas, from Louisiana and the Caribbean south to Argentina, but is not currently known elsewhere.