Opisthosporidia is a superphylum of intracellular

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s with amoeboid vegetative stage, defined as a common group of

eukaryotic Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

groups

Microsporidia Microsporidia are a group of spore-forming unicellular parasites. These spores contain an extrusion apparatus that has a coiled polar tube ending in an anchoring disc at the apical part of the spore. They were once considered protozoans or prot ...

, Cryptomycota (also known as Rozellida, Rozellomycota, or Rozellosporidia) and Aphelidea. They have been considered to represent a monophyletic lineage with shared ecological and structural features, being a sister clade of the

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 ...

. Together with the Fungi they represent a sister clade of the

Cristidiscoidea Cristidiscoidea or Nucleariae is a proposed basal holomycota clade in which Fonticula and Nucleariida emerged, as sister of the fungi. Since it is close to the divergence between the main lineages of fungi and animals, the study of Cristidiscoide ...

, together forming the

Holomycota Holomycota or Nucletmycea are a basal Opisthokont clade as sister of the Holozoa. It consists of the Cristidiscoidea and the kingdom Fungi. The position of nucleariids, unicellular free-living phagotrophic amoebae, as the earliest lineage of Holo ...

. Several other basal groups of the freshwater, marine and soil-inhabiting Holomycota were identified in recent studies, as the 'basal clone group 1' (BCG1=NCLC1), 'basal clone group 2' (BCG2), 'basal marine group' (NAMAKO-37), 'basal group GS01', the inner relationships of Opisthosporidia were clarified and their

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic grou ...

questioned: Cryptomycota and Microsporidia were proposed to join the phylum Rozellomycota, while Aphelidea were considered as a separate, though related phylum and all these groups were considered basal lineages of the kingdom Fungi. Instead of probably

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

Opisthosporidia, the phyla

Rozellomycota Cryptomycota ('hidden fungi'), Rozellida, or Rozellomycota are a clade of micro-organisms that are either fungi or a sister group to fungi. They differ from classical fungi in that they lack chitinous cell walls at any trophic stage in their lif ...

and

Aphelidiomycota Aphelida is a phylum of Fungi that appears to be the sister to true fungi. Taxonomy * Phylum Aphelidiomycota Tedersoo 2018 phelida Karpov, Aleoshin & Mikhailov 2014ref> ** Class Aphelidiomycetes Tedersoo 2018 phelidea Gromov 2000*** Order Aphel ...

(or

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

subkingdoms Rozellomyceta and Aphelidiomyceta) are recently applied in some taxonomical systems of the kingdom Fungi for the basal lineages, and the other fungal lineages are grouped into a clade of True Fungi (Eumycota). However, the taking up of the name Rozellomycota in such a broad sense can be considered premature, especially as the structure and biological features of a larger part of these organisms are unclear as they are known only from environmental sequences. The borders between Fungi and

Protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...

a are therefore unstable and final delimitation of taxa is problematic due to poor coverage of molecular data for the representatives of the basal groups.

References

{{Taxonbar, from=Q20481166 Opisthokont unranked clades Holomycota