Peanut Butter Cup Fungus

Appearance

The fruit bodies of ''G. rufa'' are initially closed and roughly spherical to top-shaped, and resemble minute puffballs. They later open in the shape of a shallow cup, and reach diameters of 15–35 mm wide. The cup margin is curved inwards and irregularly toothed; the teeth are a lighter color than the hymenium. The interior surface of the cup, which bears the spore-bearing surface is reddish-brown to orange-brown. The exterior surface is blackish-brown, and covered with hairs that measure 7–8 μm long that give it a felt-like or hairy texture.

The flesh of the fruit body lacks any distinctive taste or odor, and is grayish, translucent, gelatinous and rubbery. The fungus sometimes has a short stem that is up to 10 mm long by 5 mm wide, but it may be missing in some specimens. Dried fruit bodies become leathery and wrinkled.

Although the fruit bodies are generally considered by North American field guides to be inedible, or of unknown edibility, in parts of Malaysia it is commonly eaten and even "prized for its edibility".

The spores are thin-walled, elliptical with narrowed ends, and covered with fine warts; they have dimensions of 10–22 by 8–10 μm. Both the spores and the asci are nonamyloid. The asci are narrow and typically 275–300 μm long. The paraphyses are slender threadlike. Ultrastructural studies have demonstrated that the development of the spore wall in ''G. rufa'' is similar to the genus ''Discina'' and to the other Sarcosomataceae, especially ''Plectania nannfeldtii''; both of these species have fine secondary wall spore ornaments.

Naming

The species was originally named ''Bulgaria rufa'' in 1832 by Lewis David de Schweinitz, based on material collected from Bethlehem, Pennsylvania. In 1913, Pier Andrea Saccardo transferred it to the genus ''Gloeocalyx'' as defined by George Edward Massee in 1901 due to its hyaline spores. Richard Korf made it the type species of his newly created ''Galiella'' in 1957, a genus that encompasses bulgarioid species with spores that feature surface warts that are made of callose-pectic substances that stain with methyl blue dye.

In 1906, Charles Horton Peck described the variety ''magna'' from material collected in North Elba, New York. Peck explained that the variety differed from the typical species in several ways: var. ''magna'' grew among fallen leaves under balsam fir trees, or among mosses on the ground, not on buried wood; it lacked a stem, and was instead broad and rounded underneath; its hymenium was more yellow-brown then the nominate variety; and, its spore were slightly longer.

The specific epithet ''rufa'' means "rusty" or reddish-brown", and refers to the color of the hymenium. The species is commonly named the "rubber cup", the "rufous rubber cup", or the "hairy rubber cup". In Sabah, it is known as ''mata rusa'' , and in Sarawak, ''mata kerbau'' .''Galiella amurense'' is similar in appearance to ''G. rufa''. It is found in north temperate Asia, where it grows on the rotting wood of Spruce trees. It has larger ascospores than ''G. rufa'', typically 26–41 by 13–16 µm. ''Bulgaria inquinans'' is similar in shape and size, but has a shiny black hymenium. ''Sarcosoma globosum'', another species found in eastern North American, is black, has a more liquid interior than ''G. rufa'', and is larger—up to 100 mm across. ''Wolfina aurantiopsis'' has a shallower, woodier fruit body with a yellowish inner surface.

Distribution

''Galiella rufa'' is found in Midwest and eastern North America, and has been collected in areas between New York and Minnesota, Missouri and North Carolina. The species is also found in Malaysia.

Habitat

''Galiella rufa'' is a saprobic species, and can grow solitarily, but more usually in groups or in clusters on decaying hardwood branches and logs. The fungus fruits in late summer and autumn. The fungus has been noted to fruit readily on logs used for the cultivation of the shiitake mushroom. The fruit bodies are readily overlooked as they blend in with their surroundings.