Chytridiomycetes is a class of fungi. Members are found in soil, fresh water, and saline estuaries. They are primitive fungi, closely related to the true fungi, and are first known from the Rhynie chert

Rhynie chert

The Rhynie chert is an Early Devonian sedimentary deposit exhibiting extraordinary fossil detail or completeness . It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield chert, is located some 700 m away...

. It has recently been redefined to exclude the taxa Neocallimastigomycota

Neocallimastigomycota

Neocallimastigomycota is a phylum of anaerobic fungi, found in the digestive tracts of herbivores. It encompasses only one family.-Discovery:...

 and Monoblepharidomycetes

Monoblepharidomycetes

Members of the Monoblepharidomycetes have a filamentous thallus that is either extensive or simple and unbranched. They frequently have a holdfast at the base. In contrast to other taxa in their phylum, some reproduce using autospores, although many do so through zoospores...

, which are now a phylum

Phylum

In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....

 and a sister-class

Class (biology)

In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...

 respectively. It includes the genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Olpidiopsis and Hypochytrium in addition to the type genus

Type genus

In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...

.

Chytridiomycetes is the major class of the phylum Chytridiomycota, which is responsible for the parasitic infections of organisms such as Daphnia and a number of amphibian species, among others.