The Auriculariales are an order of

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

in the

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

Agaricomycetes The Agaricomycetes are a class of fungi in the division Basidiomycota. The taxon is roughly identical to that defined for the Homobasidiomycetes (alternatively called holobasidiomycetes) by Hibbett & Thorn, with the inclusion of Auriculariales ...

. Species within the order were formerly referred to the " heterobasidiomycetes" or "jelly fungi", since many have gelatinous basidiocarps (fruit bodies) that produce spores on septate basidia. Around 200 species are known worldwide, placed in six or more families, though the status of these families is currently uncertain. All species in the Auriculariales are believed to be saprotrophic, most growing on dead wood. Fruit bodies of several '' Auricularia'' species are cultivated for food on a commercial scale, especially in China.

Taxonomy

History

The order was established in 1889 by German mycologist Joseph Schröter to accommodate species of fungi having "auricularioid" basidia (more or less cylindrical basidia with lateral septa), including many of the rusts and smuts. In 1922, British mycologist Carleton Rea recognized the order as containing the families Auriculariaceae and Ecchynaceae, as well as the rusts ( Coleosporiaceae and Pucciniaceae) and the smuts ( Ustilaginaceae). Many subsequent authors, however, separated out the rusts and smuts and amalgamated the remaining Auriculariales with the Tremellales. Jülich (1981) also separated out the rusts and smuts, but recognized the remaining Auriculariales as an independent order, placing within them the families Auriculariaceae, Cystobasidiaceae, Paraphelariaceae, Saccoblastiaceae, Ecchynaceae, Hoehnelomycetaceae, and Patouillardinaceae. A radical revision was undertaken in 1984, when American mycologist Robert Joseph Bandoni used

transmission electron microscopy Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a g ...

to investigate the ultrastructure of the septal pore apparatus in the Auriculariales. This revealed that species of fungi with "auricularioid" basidia were not necessarily closely related and that '' Auricularia'' had more in common with '' Exidia'' and its allies (with "tremelloid" basidia), than with other auricularioid fungi. Bandoni therefore amended the Auriculariales to include the family Auriculariaceae (with auricularioid basidia) together with the families Exidiaceae, Aporpiaceae, Hyaloriaceae, and Sebacinaceae (with tremelloid basidia). This revision was accepted by Wells (1994) who, however, amalgamated the Aporpiaceae and Hyaloriaceae (together with the Heteroscyphaceae) and added the families Patouillardinaceae (with diagonally septate basidia) and Tremellodendropsidaceae (with partly septate basidia). Roberts (1998) subsequently added the family Oliveoniaceae (with non-septate basidia).

Current status

Molecular research, based on

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis of

DNA sequences A nucleic acid sequence is a succession of bases within the nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. This succession is denoted by a series of a set of five different letters that indicate the order of the ...

, has substantially supported Bandoni's revised circumscription of the Auriculariales, but has moved the Sebacinaceae and the Tremellodendropsidaceae to their own separate orders, the Sebacinales and Tremellodendropsidales. The status of the constituent families has not yet been examined, but a clade containing ''Auricularia'' and ''Exidia'' species equates to the Auriculariaceae, whilst another containing '' Hyaloria'' and '' Myxarium'' species equates to the Hyaloriaceae.

Description

The majority of species within the Auriculariales produce gelatinous basidiocarps (fruit bodies) on dead wood. In some these are conspicuous and may be ear-shaped, button-shaped, lobed, bracket-like, or effused. Their hymenophores (spore-bearing surfaces) may be smooth, warted, veined, toothed (as in the genus '' Pseudohydnum''), cyphelloid (as in the genus '' Heteroscypha''), or poroid (as in the genera '' Elmerina'' and '' Aporpium''). Some species, however, produce dry, leathery, or web-like fruit bodies resembling those of the corticioid fungi.

Distribution and habitat

All species within the Auriculariales are thought to be saprotrophs, most of them wood-rotters. They are typically found on dead attached or fallen wood, though a few ('' Guepinia'' species) are normally found on the ground. As a group, their distribution is cosmopolitan.

Economic importance

Several species within the order are edible and two, '' Auricularia heimuer'' and '' Auricularia cornea'', are cultivated on a commercial scale, particularly in China and southeast Asia. File:Auricularia cornea 32082.jpg, File:Exidia glandulosa.jpg, File:Exidia recisa 34873 cropped.jpg, File:Guepinia helvelloides 47030.jpg, File:Myxarium nucleatum 108643403.jpg, File:Pseudohydnum.gelatinosum2.-.lindsey.jpg,

References

{{Authority control Basidiomycota orders Taxa named by Joseph Schröter Taxa described in 1889