Hyphochytridiomycetes is a class of fungus

Fungus

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...

-like organisms (sometimes classified as protists), within the Kingdom Chromalveolata.

Characteristics

They are distinguished by an anterior tinsel flagellum on their zoospores.

Also they have a rhizoidal or hypha-like vegetative system (hence the prefix "Hypho-").

Classification

Alternatively this group may be put at the phylum level; then the group will be referred to as Hyphochytridiomycota. The alternative versions Hypochytridiomycota, Hypochytridiomycetes, Hyphochytriomycota, and Hyphochytriomycetes are also sometimes seen (the last two are the ones in Index Fungorum.)

In the past the classes Hyphochytridiomycetes, Oomycetes, and Chytridiomycetes

Chytridiomycota

Chytridiomycota is a division of the Fungi kingdom. The name is derived from the Greek chytridion, meaning "little pot", describing the structure containing unreleased spores. In older classifications, chytrids were placed in the Class Phycomycetes under the subdivision Myxomycophyta of the...

 were grouped together in the now obsolete taxon Mastigomycotina

Mastigomycotina

Mastigomycotina is a former taxonomic grouping, a subdivision, of fungi that contained the classes Chytridiomycetes, Hyphochytridiomycetes, and Oomycetes.GENERAL FEATURES OF MASTIGOMYCOTINA* They produce Flagellated cells during their lifetime....

 as fungi with flagellate spores or gametes. Now the Chytridiomycetes are still considered true fungi, but the other two sub-groups are very differently classified in the kingdom Protista.

Hyphochytriomycetes is closely related to oomycetes.

Diversity

This is a relatively small group, composed of about 16 known species, which may be due in part, to sampling methods of scientists.