''Exidia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...

in the family

Auriculariaceae The Auriculariaceae are a family of fungi in the order Auriculariales. Species within the family were formerly referred to the " heterobasidiomycetes" or "jelly fungi", since many have gelatinous basidiocarps (fruit bodies) that produce spore ...

. The species are

saprotrophic Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ( ...

, occurring in attached or recently fallen dead wood, and produce gelatinous

basidiocarps In fungi, a basidiocarp, basidiome, or basidioma () is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not ...

(fruit bodies). The fruit bodies are diverse, pustular, lobed, button-shaped or cup-shaped. Several species, including the type species '' Exidia glandulosa'', have sterile pegs or pimples on their spore-bearing surface. The genus has a cosmopolitan distribution and around 20 species are currently recognized worldwide. Initial molecular research indicates the genus is artificial.

Taxonomy

''Exidia'' species were originally placed in the genus '' Tremella'' along with many other gelatinous fungi. The genus ''Exidia'' was separated from ''Tremella'' by

Fries French fries (North American English), chips (British English), finger chips (Indian English), french-fried potatoes, or simply fries, are '' batonnet'' or '' allumette''-cut deep-fried potatoes of disputed origin from Belgium and France. Th ...

in 1822, based mainly on fruit body shape. Fries initially included species now assigned to ''

Auricularia ''Auricularia'' is a genus of fungi in the family Auriculariaceae. Basidiocarps (fruit bodies) are typically gelatinous and ear-shaped, with a slightly downy to conspicuously hirsute upper surface and an under surface that is smooth, wrinkled or ...

'' within the genus. Recent molecular research has indicated that ''Exidia'' as currently circumscribed is an artificial grouping, the species not being clearly differentiated from similar, but effused species assigned to the genera ''

Exidiopsis ''Exidiopsis'' is a genus of fungi in the family Auriculariaceae. The genus has a widespread distribution and contains around 30 species. One species, ''Exidiopsis effusa'', is responsible for the formation of hair ice on dead wood. Species ...

'' and ''

Heterochaete ''Heterochaete'' is a genus of fungi in the order Auriculariales. Species produce effused, gelatinous, waxy, or leathery basidiocarps (fruit bodies) on wood, partly or wholly covered in small sterile spines or pegs. The presence of these steril ...

''. Only a few species have yet been sequenced, however.

Description

''Exidia'' fruit bodies are gelatinous, most having a distinct spore-bearing upper surface and a sterile undersurface. These surfaces are either smooth or (in some species) covered in dense or scattered sterile pegs or pimples. Fruit bodies grow either separately or in clusters, in which case they may coalesce.

Microscopic characters

''Exidia'' fruit bodies are composed of

hyphae A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

with

clamp connection A clamp connection is a hook-like structure formed by growing hyphal cells of certain fungi. It is a characteristic feature of Basidiomycetes fungi. It is created to ensure that each cell, or segment of hypha separated by septa (cross walls), rece ...

s in a gelatinous matrix. The spore-bearing surface is initially covered in a layer of branched hyphidia below which the

basidia A basidium () is a microscopic sporangium (a spore-producing structure) found on the hymenophore of fruiting bodies of basidiomycete fungi which are also called tertiary mycelium, developed from secondary mycelium. Tertiary mycelium is highly- ...

are formed. The basidia are tremelloid (ellipsoid and vertically septate), giving rise to long, sinuous sterigmata or epibasidia on which the

basidiospores A basidiospore is a reproductive spore produced by Basidiomycete fungi, a grouping that includes mushrooms, shelf fungi, rusts, and smuts. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are ...

are produced. These spores are allantoid (sausage-shaped) or less commonly oblong to cylindrical.

Representative species

*'' Exidia aeruginosa'' *'' Exidia alveolata'' *'' Exidia cartilaginea'' *'' Exidia glandulosa'' (synonym ''E. truncata'') *'' Exidia japonica'' *'' Exidia nigricans'' (synonym ''E. plana'') *'' Exidia novozealandica'' *'' Exidia pithya'' *'' Exidia pusilla'' *'' Exidia recisa'' *'' Exidia repanda'' *'' Exidia saccharina'' *''

Exidia thuretiana ''Exidia thuretiana'' (common name white brain ) is a jelly fungus in the family Auriculariaceae. The fruit bodies are white and gelatinous with brain-like folds. It is a common, wood-rotting species in Europe, typically growing on dead attached ...

References

{{Taxonbar, from=Q387146 Auriculariales Agaricomycetes genera