Hyphochytridiomycota

Hyphochytridiomycota is a phylum of "fungi" (actually classified as protists), within the Kingdom Chromalveolata. 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-").

Alternatively this group may be put at the class level inside the phylum Heterokontophyta of the protists (as in Wikipedia); then the group will be referred to as Hyphochytridiomycetes. 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 were grouped together in the now obsolete taxon Mastigomycotina 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.

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