Teleomorph, anamorph and holomorph

Fungi 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 easily be classified based on sexual characteristics; some produce both asexual and sexual states. These species are often members of the Ascomycota, but a few of them 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. 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 known from only part of their life cycle. Others retain the term "deuteromycetes," but give it a lowercase "d" and no taxonomic rank. Historically, Article 59 of the International Code of Botanical Nomenclature permitted mycologists to give asexually reproducing fungi (anamorphs) separate names from their sexual states (teleomorphs). This practice was discontinued as of 1 January 2013. However, it is essential for workers in plant pathology, mold identification, medical mycology, and food microbiology, fields in which asexually reproducing fungi are commonly encountered. == From dual system to single nomenclature ==

The separate names for anamorphs of fungi with a pleomorphic life-cycle has been an issue of debate since the phenomenon was recognized in the mid-19th century. At the International Botanical Congress in Vienna in 2005, some minor modifications were made which allowed anamorph-typified names to be epitypified by material showing the sexual stage when it was discovered, and for that anamorph name to continue to be used. 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. The Vienna Congress (2005) established a Special Committee to investigate the issue further, but it was unable to reach a consensus. Matters were becoming increasingly desperate as mycologists using molecular phylogenetic approaches started to ignore the provisions, or interpret them in different ways. ==One fungus, one name==

The International Botanical Congress in Melbourne in July 2011 made a change in the International Code of Nomenclature for algae, fungi, and plants and adopted the principle "one fungus, one name". All names now compete on an equal footing for priority. In the Shenzhen Code of 2018, a new chapter F "Names of organisms treated as fungi" was added, collecting all fungus-specific provisions including the original Article 59 into this chapter. , the latest revision of this part is the San Juan Chapter F of 2019, published as an addendum of the Shenzhen Code of 2018. The problem of choosing one name among many remains to be examined for many large, agriculturally or medically-important genera like Aspergillus and Fusarium. Articles have been published on such specific genera to propose ways to define them under the newer rules. ==See also==