The Chytridiomycota is a phylum in the kingdom Fungi, whose members produce unwalled, asexual spores that swim by means of a single, posteriorly directed flagellum. Members are microscopic saprobes or parasites found in fresh and saline water and soils. The phylum contains two classes, the Monoblepharidomycetes with one order and the Chytridiomycetes with seven orders and several undescribed groups. Orders are based on molecular and ultrastructural characters. Many species of chytrids were described without these characters and need to be re‐examined to place them in the proper orders and genera. Chytrids are important as degraders of cellulose, keratin and chitin and also as algal pathogens, sometimes controlling algal blooms. A few are plant pathogens with
Synchytrium endobioticum
causing black wart of potatoes. The rhizophydialean chytrid
Batrachochytrium dendrobatidis
grows in keratinised skin cells of amphibians and is pathogenic to many species, causing amphibian population declines on several continents and extirpation of some species.
Key Concepts:
Members of the Chytridiomycota are ubiquitous in aquatic and terrestrial habitats and can be found by microscopically examining baits placed with aquatic debris or with soil plus water.
Chytridiomycota reproduce primarily by zoospores, which are mitotically produced, contained by a membrane and motile via a posteriorly directed flagellum.
Because of convergent evolution of light microscopic characters, many genera described before the molecular era are polyphyletic and may not be placed in the correct order.
Systematics in the Chytridiomycota relies on transmission electron microscopic features of zoospores and on DNA sequence information.
Algal parasites are usually species specific and are capable of affecting population levels of planktonic algae.
Batrachochytrium dendrobatidis
is a chytrid pathogen of amphibians responsible for some amphibian population declines on at least five continents.