''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 nom ...

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

in the family Auriculariaceae. 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 ''Exidia glandulosa'' (common names black witches' butter, black jelly roll, or warty jelly fungus) is a jelly fungus in the family Auriculariaceae. It is a common, wood-rotting species in Europe, typically growing on dead attached branches of ...

'', 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 ''Tremella'' is a genus of fungi in the family Tremellaceae. All ''Tremella'' species are parasites of other fungi and most produce anamorphic yeast states. Basidiocarps (fruit bodies), when produced, are gelatinous and are colloquially classed ...

'' 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 Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maint ...

'' 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'' and '' Heterochaete''. 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 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), rec ...

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 In biology, a septum (Latin for ''something that encloses''; plural septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate. Examples Human anatomy * Interatr ...

), giving rise to long, sinuous

sterigmata In biology, a sterigma (pl. sterigmata) is a small supporting structure. It commonly refers to an extension of the basidium (the spore-bearing cells) consisting of a basal filamentous part and a slender projection which carries a spore at the ti ...

or epibasidia on which the basidiospores are produced. These spores are allantoid (sausage-shaped) or less commonly oblong to cylindrical.

Representative species

*'' Exidia aeruginosa'' *'' Exidia alveolata'' *'' Exidia cartilaginea'' *''

'' (synonym ''E. truncata'') *''

Exidia japonica ''Exidia'' is a genus of fungi in the family Auriculariaceae. The species are saprotrophic, occurring in attached or recently fallen dead wood, and produce gelatinous basidiocarps (fruit bodies). The fruit bodies are diverse, pustular, lobed, bu ...

'' *''

Exidia nigricans ''Exidia nigricans'' (common name Witches' butter) is a jelly fungus in the family Auriculariaceae. It is a common, wood-rotting species throughout the northern hemisphere, typically growing on dead attached branches of broadleaf trees. It has b ...

'' (synonym ''E. plana'') *''

Exidia novozealandica ''Exidia'' is a genus of fungi in the family Auriculariaceae. The species are saprotrophic, occurring in attached or recently fallen dead wood, and produce gelatinous basidiocarps (fruit bodies). The fruit bodies are diverse, pustular, lobed, bu ...

'' *''

Exidia pithya ''Exidia'' is a genus of fungi in the family Auriculariaceae. The species are saprotrophic, occurring in attached or recently fallen dead wood, and produce gelatinous basidiocarps (fruit bodies). The fruit bodies are diverse, pustular, lobed, bu ...

'' *''

Exidia pusilla ''Exidia'' is a genus of fungi in the family Auriculariaceae. The species are saprotrophic, occurring in attached or recently fallen dead wood, and produce gelatinous basidiocarps (fruit bodies). The fruit bodies are diverse, pustular, lobed, bu ...

'' *''

Exidia recisa ''Exidia recisa'' (common name willow brain or amber jelly roll) is a jelly fungus in the family Auriculariaceae. It is a common, wood-rotting species throughout the northern hemisphere, typically growing on dead attached twigs and branches of ...

'' *''

Exidia repanda ''Exidia'' is a genus of fungi in the family Auriculariaceae. The species are saprotrophic, occurring in attached or recently fallen dead wood, and produce gelatinous basidiocarps (fruit bodies). The fruit bodies are diverse, pustular, lobed, bu ...

'' *''

Exidia saccharina ''Exidia'' is a genus of fungi in the family Auriculariaceae. The species are saprotrophic, occurring in attached or recently fallen dead wood, and produce gelatinous basidiocarps (fruit bodies). The fruit bodies are diverse, pustular, lobed, bu ...

'' *'' Exidia thuretiana''

References

{{Taxonbar, from=Q387146 Auriculariales Agaricomycetes genera