Classification of Sub-Kingdom Protozoa

The following classification recommended by the Society of Protozoologists (Levine et.al., 1980), the subkingdom Protozoa is divided into seven phyla:

1) Sarcomastigophora, 2) Apicomplexa, 3) Myxozoa, 4) Microspora, 5) Labyrinthomorpha, 6) Ascetospora & 7) Ciliophora.

1) Phylum Sarcomastigophora;

  1. Single type of nucleus, except in Foraminiferida.
  2. Sexuality, when present, essentially syngamy.
  3. With flagella, pseudopodia or both type of locomotor organelles.

i) Subphylum Mastigophora:

  1. One or more flagella typically present in trophozoites.
  2. Asexual reproduction basically by intrakinetal (symmetrogenic) binary fission.
  3. Sexual reproduction known in some groups.

Example- Giardia, Trichomonas etc.

ii) Subphylum Sarcodina:

  1. Pseudopodia, or locomotive protoplasmic flow without discrete pseudopodia.
  2. Flagella, when present, usually restricted to developmental or other temporary stages.
  3. Body naked or with external or internal test or skeleton.
  4. Asexual reproduction by fission.
  5. Sexuality, if present, associated with flagellate or, more rarely, amoeboid gametes.
  6. Most species free-living.

Example- Entamoeba, Acanthamoeba, Naegleria etc.

iii) Subphylum Opalinata:

  1. Numerous cilia in oblique rows over entire body surface.
  2. Cytostome absent.
  3. Nuclear division accentric.
  4. Binary fission generally interkinetal.
  5. Known life cycles involve syngamy with anisogamous flagellated gametes.
  6. All parasitic.

Example- Opalina, Zelleriella etc.

2) Phylum Apicomplexa:

  1. Apical complex (visible with electron microscope), generally consisting of polar ring(s), rhoptries, micronemes, conoid, and subpellicular microtubules present at some stage.
  2. Micropore(s) generally present at some stage.
  3. Cilia absent.
  4. Sexuality by syngamy.
  5. All species parasitic.

Example- Monocystis, Gregarina, Toxoplasma, Plasmodium, Babesia etc.

3) Phylum Myxozoa:

  1. Spores of multicellular origin, with one or more polar capsules and sporoplasms.
  2. With one, two, or three (rarely more) valves.
  3. All species parasitic.

Example- Myxidium, Ceratomyxa, Trilospora etc.

4) Phylum Microspora:

  1. Unicellular spores, each with imperforate wall, containing one uninucleate or dinucleate sporoplasm and simple or complex extrusion apparatus always with polar tube and polar cap.
  2. Without mitochondria.
  3. Often, if not usually, dimorphic in sporulation sequence.
  4. Obligatory intracellular parasites in nearly all major animal groups.

Example- Burkea, Hessea, Glugea etc.

5) Phylum Labyrinthomorpha:

  1. Trophic stage, ectoplasmic network with spindle-shaped or spherical, non-amoeboid cells.
  2. In some genera amoeboid cells move within network by gliding.
  3. Zoospores produced by most species.
  4. Saprobic or parasitic on algae, mostly in marine and estuarine water.

6) Phylum Ascetospora:

  1. Spore apparently multicellular (or unicellular?).
  2. With one or more sporoplasms.
  3. Without polar capsules or polar filaments.
  4. All parasitic.

Example-  Urosporidium, Haplosporidium etc.

7) Phylum Ciliophora:

  1. Simple cilia or compound ciliary organelles typical in at least one stage of life cycle.
  2. With subpellicular infraciliature present even when surface cilia absent.
  3. Two types of nuclei, with rare exception.
  4. Binary fission transverse, but budding and multiple fission also occurs.
  5. Sexuality involving conjugation, autogamy and cytogamy.
  6. Nutrition heterotrophic.
  7. Contractile vacuole typically present.
  8. Most species free-living, but many commensal, some truly parasitic, and a large number found as phoronts on a variety of hosts.

Example-  Balantidium, Trichodina, Nyctotherus etc.

n following the classification recommended by the Society of Protozoologists (Levine et.al., 1980), the subkingdom Protozoa is divided into seven phyla:

1) Sarcomastigophora, 2) Apicomplexa, 3) Myxozoa, 4) Microspora, 5) Labyrinthomorpha, 6) Ascetospora & 7) Ciliophora.

1) Phylum Sarcomastigophora;

Single type of nucleus, except in Foraminiferida.

Sexuality, when present, essentially syngamy.

With flagella, pseudopodia or both type of locomotor organelles.

i) Subphylum Mastigophora:

One or more flagella typically present in trophozoites.

Asexual reproduction basically by intrakinetal (symmetrogenic) binary fission.

Sexual reproduction known in some groups.

Example- Giardia, Trichomonas etc.

ii) Subphylum Sarcodina:

Pseudopodia, or locomotive protoplasmic flow without discrete pseudopodia.

Flagella, when present, usually restricted to developmental or other temporary stages.

Body naked or with external or internal test or skeleton.

Asexual reproduction by fission.

Sexuality, if present, associated with flagellate or, more rarely, amoeboid gametes.

Most species free-living.

Example- Entamoeba, Acanthamoeba, Naegleria etc.

iii) Subphylum Opalinata:

Numerous cilia in oblique rows over entire body surface.

Cytostome absent.

Nuclear division accentric.

Binary fission generally interkinetal.

Known life cycles involve syngamy with anisogamous flagellated gametes.

All parasitic.

Example- Opalina, Zelleriella etc.

2) Phylum Apicomplexa:

Apical complex (visible with electron microscope), generally consisting of polar ring(s), rhoptries, micronemes, conoid, and subpellicular microtubules present at some stage.

Micropore(s) generally present at some stage.

Cilia absent.

Sexuality by syngamy.

All species parasitic.

Example- Monocystis, Gregarina, Toxoplasma, Plasmodium, Babesia etc.

3) Phylum Myxozoa:

Spores of multicellular origin, with one or more polar capsules and sporoplasms.

With one, two, or three (rarely more) valves.

All species parasitic.

Example- Myxidium, Ceratomyxa, Trilospora etc.

4) Phylum Microspora:

Unicellular spores, each with imperforate wall, containing one uninucleate or dinucleate sporoplasm and simple or complex extrusion apparatus always with polar tube and polar cap.

Without mitochondria.

Often, if not usually, dimorphic in sporulation sequence.

Obligatory intracellular parasites in nearly all major animal groups.

Example- Burkea, Hessea, Glugea etc.

5) Phylum Labyrinthomorpha:

Trophic stage, ectoplasmic network with spindle-shaped or spherical, non-amoeboid cells.

In some genera amoeboid cells move within network by gliding.

Zoospores produced by most species.

Saprobic or parasitic on algae, mostly in marine and estuarine water.

Example-

6) Phylum Ascetospora:

Spore apparently multicellular (or unicellular?).

With one or more sporoplasms.

Without polar capsules or polar filaments.

All parasitic.

Example- Urosporidium, Haplosporidium etc.

7) Phylum Ciliophora:

Simple cilia or compound ciliary organelles typical in at least one stage of life cycle.

With subpellicular infraciliature present even when surface cilia absent.

Two types of nuclei, with rare exception.

Binary fission transverse, but budding and multiple fission also occurs.

Sexuality involving conjugation, autogamy and cytogamy.

Nutrition heterotrophic.

Contractile vacuole typically present.

Most species free-living, but many commensal, some truly parasitic, and a large number found as phoronts on a variety of hosts.

Example- Balantidium, Trichodina, Nyctotherus etc.

12 thoughts on “Classification of Sub-Kingdom Protozoa”

  1. needed topics on the following:-
    1)salient features of protozoa
    2)some common protozoans and their importance
    3)important terms (with details) related to protozoa.
    may i help you?
    THANKING YOU.

  2. well done. But more of the orders and families should go along with this, or at least a brief and reasonable summary of d kingdom- phyllum- sub phyllum- class-sub classes- orders-families-species

  3. The information should be more detailed on the class,order family,genus and species.thanks for putting this up, it really helped.

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