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SYNOPTIC DESCRIPTION OF THE PHYLUM PSEUDOCILIATA

SYNOPTIC DESCRIPTION OF THE PHYLUM PSEUDOCILIATA (CAVALIER-SMITH 1993)

EUKARYA> EXCAVATA> DISCICRISTATAE> PSEUDOCILIATA
The following description of the Phylum was taken from Corliss (1990), Patterson (1999), and Cavalier-Smith (2003a).

I. SYNONYMS: pseudociliates, stephanopogonids.

II. NUMBER: Poorly studied, 4 species known.

III. PHYLUM CHARACTERISTICS:

  • A. Structure and Physiology
    • Cell Form: Unicellular; dorsoventrally flattened with a large, apical cytostome (text with tooltip) Cytostome (literally cell mouth) is a permanent opening into the cell into which food particles move and are incorporated into food vacuoles. , sometimes with barbs.
    • Flagella: Many unpaired flagella arranged in kineties (text with tooltip) Kineties (kinety) provide the underlying structure of flagellar roots found in ciliates (and others like the pseudociliata) and allow for coordination of the flagella. ; no hairs, scales or paraxonemal rods (text with tooltip) A paraxial rod is a stiffened rod-like structure that lies alongside the axoneme of one of the flagella in the Euglenidae. . Cells generally flagellated all over.
    • Basal Bodies (text with tooltip) Basal bodies (also called kinetosomes) are organelles that are not membrane-bound. All eukaryotic flagella (also called undulipodia) are underlain or attached to the cell by the basal body. The basal body is a microtubular structure with the general formula 9(3)+0. They are indistinguishable from centrioles. : Unpaired but associated with a cone-like basket of microtubules that associate with non-microtubular ribbons that lie beneath the cell membrane and connect the rows of basal bodies.
    • Cell Covering: Dorso-ventrally flattened and covered with flagella in kinities.
    • Chloroplasts (text with tooltip) Chromoplast is the general term for a photosynthetic organelle. Technically, a chloroplast is a particular chromoplast in which the dominant chlorophylls are A and B. : No chloroplasts.
    • Food Reserves: Not reported.
    • Mitochondria: Their cristae are saccate or discoid (text with tooltip) Discoid cristae (crista, sing.) are swollen tube-like cristae within certain mitochondria. .
    • Golgi (text with tooltip) Golgi apparatus (also called dictyosome) is an internal membrane system of stacked flattened sacs. They occur in nearly all eukaryotes and are involved in storing and secreting cellular products. : Present.
    • Nucleus:
    • Centrioles: Not reported.
    • Inclusions and Ejectile Organelles:
    • Food vacuoles and extrusosomes (microtubular rods in square pattern).
  • B. MITOSIS, MEIOSIS AND LIFE HISTORY
    • Mitosis: ?
    • Meiosis: Not reported.
    • Sexual Reproduction and Life History: Not reported.
  • C. Ecology: Marine; free-living, saprobic, and phagotrophic.
LITERATURE CITED

Cavalier-Smith, T. 2003a. Protist phylogeny and the high-level classification of Protozoa. European Journal of Protistology. 39:338-348.

Corliss, J. O. 1990. Opalinta. In: Margulis, L., J. O. Corliss, M. Melkonian, and D. J. Chapman, eds. 1990. Handbook of the Protoctista; the Structure, Cultivation, Habits and Life Histories of the Eukaryotic Microorganisms and Their Descendants Exclusive of Animals, Plants and Fungi. Jones and Bartlett Publishers. Boston. pp. 239-245.

Lipscomb, D. L. and J. O. Corliss. 1982. Stephanopogon, a phylogenetically important “ciliate,” shown by ultrastructural studies to be a flagellate. Science. 215(4530): 303 – 304.

Patterson, D. J. 1999. The diversity of eukaryotes. American Naturalist. 154 (Suppl.): S96–S124. [C,L]
By Jack R. Holt. Last revised: 02/15/2012
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