Chytridiomycetes are water-inhabiting fungi, often parasitic on algae and oomycetes, or soil inhabitants, some of which are parasitic on vascular plants. A few chytrids parasitize animal eggs and protozoa, while others are saprobic on the decaying remains of plants. Multigene phylogenetic analyses, new culture techniques, and additional collections of Chytridiomycetes have revealed greater diversity and led to increased numbers of orders in which to classify about 700 species in under 90 genera. Today there are 10 described orders of Chytridiomycetes: Chytridiales, Spizellomycetales, Cladochytriales, Rhizophydiales, Polychytriales, Rhizophlyctidales, Lobulomycetales, Synchytriales, Gromochytriales, and Mesochytriales. An exemplar life cycle is that of Chytriomyces hyalinus, which forms a well-developed rhizoidal system within its substrate. The sporangium that develops from the encysted zoospore has a saucer-shaped operculum from which zoospores escape into a fib...
Cryptomycota plus Microsporidia are sisters to the remaining lineages of Kingdom Fungi. (Note: Rozellomycota is another name for Cryptomycota based on the genus Rozella and the principle of autotypification. Cryptomyces is a genus in Ascomycota and cannot be used to typify Cryptomycota.) Cryptomycota consists of a handful of described taxa and taxa that are known only from environmental samples. One described taxon is Rozella, a biotrophic intracellular parasite of other zoosporic fungi of Chytridiomycota and Blastocladiomycota and oomycetes of the kingdom Stramenopila. There are few additionally described genera and species of Cryptomycota, but environmental sampling using molecular markers has revealed a phylogenetically diverse assemblage of fungi detected in soils, marine, and freshwater sediments, and oxygen-depleted environments. Some environmental Cryptomycota produces zoospores with a single, smooth flagellum, but chitin, a cell wall carbohydrate produced by mo...
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