Zygomycotina

Sub-division: Zygomycotina:- It includes 2 classes -

a. Zygomycetes:- 

> The class zygomycetes derives its name from the thick-walled resting spores, the zygospores formed as a result of the complete fusion of the protoplasts of two equal or unequal gametangia. 

> It comprises 450 species which are grouped under 70 genera.

> They all are terrestrial molds which show a wide range in their habit. 

> Most of them are saprobes. Among these some are soil saprophytes and others coprophilous (growing on dung).

> The parasitic species include pin molds which attack fungi, insects or protozoa. Some are facultative weak parasites (Rhizopus sexualis) of higher plants. A few are specialized parasites of animals. A very few occur as obligate parasites of other Zygomycetes.

> The members are saprobes or weak parasites on plants to specialized parasites on animals. A few occur on dung thus coprophilous in nature.

> The thallus usually consists of well developed, branched, filamentous, and coenocytic mycelium; some members possess very much reduced septate mycelium. In some cases, the coenocytic mycelium produces rhizoids and adheres to hard surfaces with their help.

> The cell wall is mainly composed of chitosan-chitin.

> The asexual reproduction takes place usually by means of non-motile sporangiospores, called aplanospores, but some also reproduce by chlamydospores or by oidia formation.

> The sexual reproduction takes place by means of gametangial copulation, resulting in the formation of thick-walled zygospores.

> The zygospore germinates by producing a germ sporangiophore that terminally bears a germ sporangium.

> Classification:-

5 Orders:-

a. Mucorales:- 

3 Families:-

i. Mucoraceae:- Eg.- Mucor, Rhizopus

ii. Syncephalastraceae:- Eg.- Syncephalastrum

iii. Pilobolaceae:- Eg.- Pilobolus

b. Dimargaritales:- Eg.- Dimargaris

c. Endogonales:- Eg.- Endogone

d. Entomophthorales:- Eg.- Entomophthora

e. Zoopagales:- Eg.- Cytopage

b. Trichomycetes:- 

> Trichomycetes, includes organisms that are clearly protozoans though they were mistakenly

classified as fungi for a long time, and are still called fungi by many people who should know

better.

> These extremely common organisms live only in the digestive tracts of insects and other

arthropods, generally as commensals, sometimes as pathogens or symbionts (mutualists), which

are associated with, although not penetrating, the cuticle lining the digestive tracts of the host

animal.

> Their hosts include terrestrial, marine and freshwater arthropods, most commonly midges

(Chironomidae), mosquitoes (Culicidae), black flies (Simuliidae), beetles (Coleoptera), stoneflies

(Plecoptera), and mayflies (Ephemeroptera), as well as several millipedes (Diplopoda) and

crustaceans.

> Classification:-

4 Orders:-

a. Amoebidiales:- Eg.- Amoebidium

b. Asellariales:- Eg.- Asellaria

c. Eccrinales:- Eg.- Enterobryus

d. Harpellales:- Eg.- Harpella, Smittium