ABSTRACT
The Chytridiomycota (chytrids) are fungi that have a motile stage involving posteriorly uniflagellate (in most cases) zoospores.l,2 These organisms are widespread in terrestrial and aquatic ecosystems where many are saprophytes, especially utilizing polymeric organic substrates. Others are microscopic parasites of various soil-and water-inhabiting organisms (algae, rotifers, nematodes, tardigrades, other fungi, including chytrids) as well as plants and amphibians. In terms of size, in most cases chytrids do not form visible growths. Dayal3 has noted that these organisms “rarely develop in sufficient abundance to be recognized directly in the field” (p. 292). The chytrids are basal to the true fungi. Evidence of an Allomyces-like organism has been found in the Devonian Rhynie Chert,4 and the nonzoosporic fungi appear to have separated from the chytrids approximately 550 million years ago, as discussed by Berbee and Taylor.5 The fungi are grouped within the opisthokonts, (Baldauf6,7), a clade that includes the animals, choanoflagellates, and microsporidians.
