Auricularia nigricans


Auricularia nigricans is a species of fungus in the family Auriculariaceae. Basidiocarps (fruitbodies

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" due to the habitat description being "ad terra", 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.

''Auricularia polytricha''

Auricularia polytricha was originally described as Exidia polytricha in 1834 in the work Voyage aux Indes-Orientales Botanique. Pt. 2. Cryptogamie. Although this record of the voyage was by Belanger, Montagne was the person who actually put it the form of a description, hence his author citation. The year 1834 was given in Montagne's later work. There is a protologue in French in the Voyage, with the location "Sur le bois mort, dan las Gâtes orientales, prés de Gengy, presqu'ile de l'Inde". The combination Auricularia polytricha appeared in Saccardo's Syll. fung. VI. This newer protologue gives a longer list of localities:

ad ligna in India orient, in Java, in Ceylon, in Mexico, in ins. Cuba Amer. centr, in Brasilia, pr. Concepcion del Uruguay, Waima Novae Zelandiae, Maungaroa, Waitaki, Coromandel, Westland, Ohaeawai, Honkianga, Wellington, in Hoew's et Chat's isl., ins. Tahiti.
on wood in East India , in Java, in Ceylon, in Mexico, in the island of Cuba, Central America, in Brazil near Concepcion del Uruguay, Waima New Zealand, Maungaroa, Waitaki, Coromandel, Westland, Ohaeawai, Hokianga, Wellington, Howe's and Chat's islands , island of Tahiti.

Lowy's 1952 monograph places the type locality of Auricularia polytricha in Jamaica instead of the Indian peninsula. It is unclear whether this is his change or by an earlier author. The synonymization by Looney specifically specifies A. polytricha sensu auct. amer. without making a judgement on other uses of the name. Wu et al. made an error by disregarding the "sensu" specifier and stating that A. polytricha was originally described from Jamaica.
The East Asian sense of Auricularia polytricha started with Patouillard and Olivier, according to Wu et al.. In any case, there is no surviving collection from Belanger, so there is no way to determine whether the 1834 collection is A. nigricans, A. cornea, or a different species altogether.
Index Fungorum search lists the following infraspecific names under Auricularia polytricha:
NameAuthorityLocality
A. p. f. leucochroma Kobayasi 1981On dead trunk of Hibiscus glaber: Ogasawara-shoto, Japan
A. p. f. polytricha Sacc. 1885Same as original
A. p. f. tenuisKobayasi 1942Micronesia
A. p. var. argenteaD.Z. Zhao & Chao J. Wang 1991 On dried wood of Ulmus: Hebei, China
A. p. var. polytricha Sacc. 1885Same as original

Although Species Fungorum synonymize all listed above to A. nigricans, the two names described in East Asia do not fall into the known range of A. nigricans. Indeed, Wu et al. found that the collection for A. p. var. argentea belongs in A. cornea.

Description

Auricularia nigricans forms thin, rubbery-gelatinous fruit bodies that are ear-shaped and up to across and 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, 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.