In this article we will discuss about the classification of chytridiomycetes.
1. Chytridiales:
It is by far the largest order and includes the most primitive members of the class Chytridiomycetes. The somatic phase is a microscopic, holocarpic or eucarpic, single-celled structure which in some species is drawn out at one point into fine branching extensions constituting the rhizomycelium.
True mycelium is lacking. The zoospore has a refractive oil globule but may lack a nuclear cap. It swims with a hopping movement or creeps over solid substratum like an amoeba.
2. Harpochytriales:
It is a small order represented by two genera Harpochytrium and Oedogoniomyces. They are placed in the family Harpochytriaceae.
3. Blastocladiales:
The vegetative body is a typical mycelium. Sexual reproduction is or aniso-planogamous. The sporangia are thick-walled and resistant. The zoospores has no refractive oil globule but has a nuclear cap. It swims evenly.
4. Monoblepharidales:
The vegetative body is a typical mycelium as in the Blastocladiales. Sexual reproduction is heterogamous and takes place by the fusion of a motile male gamete and a non-motile female gamete. Resistant sporangia are lacking. The zoospores are similar to those of the Blastocladiales.
Sparrow (1973) divided the class into the following four orders on the basis of vegetative characters, zoospore characteristics, mode of plasmogamy and resting spores.
The classification and key to the orders of the class Chytridiomycetes are given below:
Three of the four orders viz. Chytridiales, Blastocladiales and Monoblepharidales are being described in some detail.