Cryptomycota ('hidden fungi'), Rozellida, or Rozellomycota are a clade of micro-organisms that are either

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 ...

or a sister group to fungi. They differ from classical fungi in that they lack chitinous cell walls at any

trophic Trophic, from Ancient Greek τροφικός (''trophikos'') "pertaining to food or nourishment", may refer to: * Trophic cascade * Trophic coherence * Trophic egg * Trophic function * Trophic hormone * Trophic level index * Trophic level ...

stage in their lifecycle, as reported by Jones and colleagues in 2011. Despite their unconventional feeding habits, chitin has been observed in the inner layer of

resting spore A resting spore is a resistant cell, used to survive adverse environmental conditions. Resting spore is a term commonly applied to both diatoms and fungi. In fungi A resting spore can be a spore created by fungi which is thickly encysted (has a ...

s, and in immature resting spores for some species of '' Rozella'', as indicated with calcofluor-white stain as well as the presence of a fungal-specific chitin synthase gene. Rozellida were first detected as DNA sequences retrieved from a freshwater laboratory enclosure.

Phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

analysis of these sequences formed a unique terminal clade of then unknown affiliation provisionally called after the first clone in the clade: LKM11. The only formally described genus in the clade is ''Rozella'', which was previously considered a chytrid. The existence of related organisms was known from

environmental DNA Environmental DNA or eDNA is DNA that is collected from a variety of environmental samples such as soil, seawater, snow or air, rather than directly sampled from an individual organism. As various organisms interact with the environment, DNA ...

sequences. Additional members of the group were isolated in 2011 by a team led by Thomas Richards, from the Natural History Museum in London, and also an evolutionary geneticist at the

University of Exeter , mottoeng = "We Follow the Light" , established = 1838 - St Luke's College1855 - Exeter School of Art1863 - Exeter School of Science 1955 - University of Exeter (received royal charter) , type = Public , ...

, UK. The team used DNA techniques to disclose the existence of unknown genetic material dredged from the university pond. Once they had a few unknown sequences they fluorescently labeled small DNA sequences and let them bind to the matching DNA in the whole sample (

fluorescence in situ hybridization Fluorescence ''in situ'' hybridization (FISH) is a molecular cytogenetic technique that uses fluorescent probes that bind to only particular parts of a nucleic acid sequence with a high degree of sequence complementarity. It was developed by ...

). Under

fluorescence microscopy A fluorescence microscope is an optical microscope that uses fluorescence instead of, or in addition to, scattering, reflection, and attenuation or absorption, to study the properties of organic or inorganic substances. "Fluorescence microscop ...

, they could see that the possessor cells were ovoid in shape and 3–5

micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

s across. They then established that the cryptomycota were present in other samples taken from further freshwater environments, soils and marine sediments. The common characteristic of the clade members is that they lack the chitinous cell walls present in almost all previously discovered fungi (including

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 pr ...

) and which are a major feature of the kingdom. Without the chitin the cryptomycota can be

phagotrophic Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is c ...

parasites that feed by attaching to, engulfing, or living inside other cells. Most known fungi feed by

osmotrophy Osmotrophy is a feeding mechanism involving the movement of dissolved organic compounds by osmosis for nutrition. Organisms that use osmotrophy are called osmotrophs. Some mixotrophic microorganisms use osmotrophy to derive some of their energy. ...

—taking in nutrients from outside the cell.

Taxonomy

* Phylum Rozellomycota ** Class Rozellidea Cavalier-Smith 2013 s.s. *** Order Rozellida Cavalier-Smith 2013 s.s. **** Genus '' Mitosporidium'' Haag et al. 2014 **** Genus '' Morellospora'' Corsaro et al. 2020 **** Genus '' Nucleophaga'' Dangeard 1895 **** Genus '' Paramicrosporidium'' Corsaro et al. 2014 **** Genus '' Rozella'' Cornu 1872

References

{{Taxonbar, from=Q1142300 Opisthokont orders Holomycota