Classification of Subkingdom Protozoa

In 1980 Levine et al. proposed a detailed classification of Protozoa which was published in the journal of Protozoology (1980). They have uplifted the phylum Protozoa into Subkingdom Protozoa. This subkingdom Protozoan has been divided into seven Phyla. The phylum Sarcomastigophora has been divided into three Subphyla. These three subphyla have been divided into 15 classes.

Phylum-I: Sarcomastigophora:
1. Locomotory organs pseudopodia or flagella.
2. Nucleus monomorphic
3. No spore formation takes place.
4. Reproduction by fission or by syngamy.

Phylum-II: Labyrinthomorpha:
1. Locomotory organs are flagella, so they are called flagellates.
2. Body is covered by pellicles.
3. They can be free-living or parasitic.
4. Number of flagella may be one, two, or many.
5. Some may possess undulating membranes.
6. Chromatophores present in free-living forms, absent in parasites.
7. Reproduction by binary fission, fission occurs through longitudinal axes,
Examples – Euglena, Volvox, Noctiluca, Chilomonas, Giardia, Trypanosoma, etc.

Phylum-III: Apicomplexa:
1. It possesses an apical complex that can be seen under an electron microscope only.
2. Generally possesses one or two polar rings.
3. Presence of microfibrils which help in locomotion.
4. Subpellicular microtubules are present at any stage.
5. Microspores may be present at a certain stage.
6. Cilia are never present in gametes flagella may be present.
7. Reproduction generally by syngamy in some cases asexual reproduction may take place.
8. All are generally intercellular parasites.
9. Spores are formed, and sporozoites develop within spores.
10. If gametocytes are produced, then they are of two types, i.e, macrogametocytes, and microgametocytes.

Phylum-IV: Microspora:
1. Spore single-celled, spore wall is without any pore.
2. Sporoplasm is with one or two nuclei.
3. Spores with complex organelles for the expulsion of sporoplasm.
4. Polar caps and polar tubes are always present.
5. Mitochondria absent.
6. During spore formation it becomes dimorphic.
7. Always intercellular parasite.
Examples – Amphiacantha, Burkea, Amblyspora, Nosema, etc.

Phylum-V: Ascetospora:
1. Spores are generally multicellular and may be single-celled.
2. Sporoplasm may be one, two, or many.
3. Polar capsule and polar filament are absent.
4. All are parasites.
5. Sporoplasm may be created from the bud of sporoplasm.
6. Spore walls maybe with pores or without pores. If pores are present they are covered by valves or may be protected by a diaphragm inside.
Examples – Marteilia, Urosporidium, Paramyxa, etc.

Phylum-VI: Myxozoa:
1. Multicellular origin of spores.
2. Polar capsule one to many.
3. Sporoplasm one or two.
4. Spore is composed of one to 3 valves.
5. All are parasites in the blood or coelom or cells of cold-blooded vertebrates.
6. Polar capsule with coiled polar filament.
Examples: Myxidium, Myxobolus, Triactinomyxon, etc.

Phylum-VII: Ciliophora:
1. Locomotory organs are simple cilia or complex ciliated organelles.
2. Nucleus are two types, one micronucleus, and another macronucleus.
3. Micronucleus is for reproduction while the macronucleus performs other functions of the body.
4. Conjugation takes place through the union of the micronucleus.
5. Autogamy may take place but free gametes aren’t formed.
6. Presence of cytostome and cytpyge.
7. Nutrition mixotrophic or heterotrophic.
8. Cilia or complex ciliated organ present.
9. Infraciliary system and cytostome present.
10. Anterior part of the body contains buccal ciliature.
11. Free swimming or sessile.
Examples: Paramoecium, Vorticella, Nyctotherus, Balantidium, Entodinium, etc.