Teleomorph, anamorph and holomorph
Encyclopedia
The terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla
Ascomycota
and Basidiomycota
.
are classified primarily based on the structures associated with sexual reproduction
, which tend to be evolutionarily conserved. However, many fungi reproduce only asexually, and cannot be easily placed in a classification based on sexual characters; some produce both asexual and sexual states. These problematic species are often members of the Ascomycota
, but may also belong to the Basidiomycota
. Even among fungi that reproduce both sexually and asexually, often only one method of reproduction can be observed at a specific point in time or under specific conditions. Additionally, fungi typically grow in mixed colonies and sporulate amongst each other. These facts have made it very difficult to link the various states of the same fungus. At present Article 59 of the International Code of Botanical Nomenclature permits mycologists to give asexually reproducing fungi (anamorphs) separate names from their sexual states (teleomorphs). When names are available for both anamorph and teleomorph states of the same fungus, the holomorph either takes the teleomorph name, or it can under some circumstances take the anamorph name if it is subsequently epitypified with a teleomorph.
Fungi that are not known to produce a teleomorph were historically placed into an artificial phylum, the "Deuteromycota", also known as "Fungi Imperfecti", simply for convenience. Some workers hold that this is an obsolete concept, and that molecular phylogeny
allows accurate placement of species which are only known from part of their life cycle. Others retain the term deuteromycetes, but give it a lowercase "d" and no taxonomic rank.
The dual naming system can be confusing for novices. It is essential for workers in plant pathology, mold identification, medical mycology, and food microbiology, fields in which asexually reproducing fungi are commonly encountered.
The 1995 edition of the influential Ainsworth and Bisby’s Dictionary of the Fungi sought to replace the term anamorph with mitosporic fungus and teleomorph with meiosporic fungus, based on the idea that the fundamental distinction is whether mitosis
or meiosis
preceded sporulation. This is a controversial choice because it is not clear that the morphological differences which traditionally define anamorphs and teleomorphs line up completely with sexual practices, or whether those sexual practices are sufficiently well understood in some cases.
Phyla
Phyla, the plural of phylum, may refer to:* Phylum, a biological taxon between Kingdom and Class* Phylum , in linguistics, a large division of possibly related languagesPhyla, as a singular, may refer to:...
Ascomycota
Ascomycota
The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya. Its members are commonly known as the Sac fungi. They are the largest phylum of Fungi, with over 64,000 species...
and Basidiomycota
Basidiomycota
Basidiomycota is one of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya within the Kingdom Fungi...
.
- Teleomorph: the sexual reproductive stage (morph), typically a fruiting body.
- Anamorph: an asexual reproductive stage (morph), often mold-like.
When a single fungus produces multiple morphologically distinct anamorphs, these are called synanamorphs. - Holomorph: the whole fungus, including anamorphs and teleomorph.
Teleomorphs, anamorphs, and the naming of fungi
FungiFungus
A fungus is a member of a large 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, Fungi, which is separate from plants, animals, and bacteria...
are classified primarily based on the structures associated with sexual reproduction
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
, which tend to be evolutionarily conserved. However, many fungi reproduce only asexually, and cannot be easily placed in a classification based on sexual characters; some produce both asexual and sexual states. These problematic species are often members of the Ascomycota
Ascomycota
The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya. Its members are commonly known as the Sac fungi. They are the largest phylum of Fungi, with over 64,000 species...
, but may also belong to the Basidiomycota
Basidiomycota
Basidiomycota is one of two large phyla that, together with the Ascomycota, comprise the subkingdom Dikarya within the Kingdom Fungi...
. Even among fungi that reproduce both sexually and asexually, often only one method of reproduction can be observed at a specific point in time or under specific conditions. Additionally, fungi typically grow in mixed colonies and sporulate amongst each other. These facts have made it very difficult to link the various states of the same fungus. At present Article 59 of the International Code of Botanical Nomenclature permits mycologists to give asexually reproducing fungi (anamorphs) separate names from their sexual states (teleomorphs). When names are available for both anamorph and teleomorph states of the same fungus, the holomorph either takes the teleomorph name, or it can under some circumstances take the anamorph name if it is subsequently epitypified with a teleomorph.
Fungi that are not known to produce a teleomorph were historically placed into an artificial phylum, the "Deuteromycota", also known as "Fungi Imperfecti", simply for convenience. Some workers hold that this is an obsolete concept, and that molecular phylogeny
Molecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
allows accurate placement of species which are only known from part of their life cycle. Others retain the term deuteromycetes, but give it a lowercase "d" and no taxonomic rank.
The dual naming system can be confusing for novices. It is essential for workers in plant pathology, mold identification, medical mycology, and food microbiology, fields in which asexually reproducing fungi are commonly encountered.
The 1995 edition of the influential Ainsworth and Bisby’s Dictionary of the Fungi sought to replace the term anamorph with mitosporic fungus and teleomorph with meiosporic fungus, based on the idea that the fundamental distinction is whether mitosis
Mitosis
Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...
or meiosis
Meiosis
Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....
preceded sporulation. This is a controversial choice because it is not clear that the morphological differences which traditionally define anamorphs and teleomorphs line up completely with sexual practices, or whether those sexual practices are sufficiently well understood in some cases.