They are classified into 7 divisions, distinguished by the presence or absence of a Plasmodium or pseudo-plasmodium. Further named as Division Myxomycota (fungi with plasmodia or pseudo-plasmodia) while the majority of fungi consist of filamentous structure and named as Eumycota.
Division I: Myxomycota:
It consists of four classes:
Class I:
Acrasiomycetes:
Assimilative phase is free living amoebae which unite as a pseudo-plasmodium before reproduction.
Class II:
Hydromyxomycetes:
Plasmodium forming a network (net Plasmodium)
Class III:
Myxomycetes:
Plasmodium is saprobic, free-living.
Class IV:
Plasmodiophoromycetes:
Plasmodium is parasitic within cell of the host plant.
Division II: Eumycota:
Divided into five major groups, distinguished from each other as shown below:
Subdivision 1-Mastigomycotina:
Motile cells (zoospores) present. Perfect stage spores are typically oospores.
Subdivision 2-Zygomycotina:
Perfect-state spores are zygospores.
Subdivision 3-Ascomycotina:
Perfect-state spores are ascospores.
Subdivision 4-Basidiomycotina:
Perfect-state spores are basidiospores.
Subdivision 5-Deuteromycotina:
Perfect-state is absent.
Subdivision I: Mostigomycotina
Mastigomycotina is divided into three classes:
Class I-Chytridiomycetes:
Zoospores are posteriorly uniflagellate (flagella whiplash type).
Class II-Hyphochytridiomycetes:
Zoospores are anteriorly uniflagellate (flagella-tinsel type).
Class III-Oomycetes:
Zoospores biflagellate (posterior flagellum whiplash type anterior tinsel type); cell wall consists of cellulose.
Subdivision II-Zygomycotina:
Zygomycotina is divided into two classes.
Class I-Zygomycetes:
This class comprises of two orders: the Mucorales and Entomophthorales. Mucorales are ubiquitous in soil and dung (mostly saprophytes), entomophthorales include a number of insect parasites.
Class II-Trichomycetes:
It is a group of uncertain affinity and is mostly parasitic in the guts of arthropods e.g. insect larvae, and millipedes.
Subdivision III-Ascomycotina:
Ascomycotina consists of six classes.
Class I-Hemiascomycetes:
In this asococarps and ascogenous hyphae lacking; thallus yeast like or mycelial.
Class II-Loculoascomycetes:
Ascocarps and ascogenous hyphae present; thallus mycelial, asci are bi-tunicate; ascocarp an ascostroma.
Class III-Plectomycetes:
Asci typically uni-tunicate; if bi-tunicate, ascocarp an apothecium. Asci evanescent, scatterd within the astomous ascocarp which is typically a cleistothecium; ascospores aseptate.
Class IV-Laboulbenomycetes:
Asci regularly arranged within the ascocarp as a basal or peripheral layer. Exparasites of arthropods; thallus reduced; ascocarp a perithecium; asci inoperculate.
Class V-Pyrenomycetes:
Not exo-parasites on arthropods, ascocarp typically a perithecium which is usually ostiolate; asci inoperculate with an apical pore or slit.
Class VI-Discomycetes:
Ascocarp an apothecium or a modified apothecium, frequently macrocarpic, epigean or hypogean; asci inoperculate or operculate.
Subdivision IV- Basidiomycotina:
Basidiomycotina consists of three classes.
Class I-Teliomycetes:
In these basidiocarp is lacking and replaced by teliospores or chlamydospores (encysted pro-basidia) grouped in sori or scattered within the host tissue; parasitic on vascular plants.
Class II- Hymenomycetes:
In such cases basidiocarp usually well developed, basidia typically organised as a hymenium; saprobic or rarely parasitic. Basidiocarp typically gymnocarpous or semiangiocarpous; basidia (phragmbasidicy) or holobasidia; basidiospores balistospores type.
Class III-Gasteromycetes:
Basidiocarp is typically angiocarpous; basidia holobasidia, basidiospores not ballistospores.
Subdivision V- Deuteromycotina:
Ainsworth (1973) classified into three classes.
Class I-Blastomycetes:
Budding (yeast or yeast like) cells with or without pseudo mycelium; true mycelium lacking or not well developed.
Class II-Hyphomycetes:
Mycelium well developed assimilative budding cells absent. Mycelium sterile or bearing spores directly or on special branches (sporophores) which may be variously aggregated but not in pycnidia or acervuli.
Class III-Coelomycetes:
Spores are found in acervuli or pycnidia.