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SYNOPTIC DESCRIPTION OF THE PHYLUM METAMONADA

SYNOPTIC DESCRIPTION OF THE PHYLUM METAMONADA (GRASSE’ 1952)

EUKARYA> EXCAVATA> EUEXCAVATA> METAMONADA
METAMONADA LINKS

Introduction

Hierarchical Classification

The following descriptions come from Vickerman (1990), Brugerolle and Mignot (1990), Dyer (1990c), Lee et al. (1985), Grell (1973), Kudo (1966), Margulis and Schwartz (1998), Patterson (1999), Taylor (1999), Cavalier-Smith (2003a and 2003b), and Simpson (2003).

I. SYNONYMS: pyrsonymphids, some polymastigotes, axostylids.

II. NUMBER: >300 species known.

III. PHYLUM CHARACTERISTICS:

  • A. Structure and Physiology
    • Cell Form: Unicellular.
    • Flagella: Occur in groups of four; usually 3 anteriorly (text with tooltip) An anteriorly-directed flagellum extends in the direction of the motion of the motile cell. The interpretation is that the flagellum functions by pulling the cell. and the 4th posteriorly-directed or recurrent (text with tooltip) Recurrent flagella bend to the posterior end of the cell. Typically, they are identified as recurrent when anteriorly-directed flagella are present. . The posterior flagellum has two vanes, longitudinal flanges.
    • Basal Bodies: 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. orthogonal; microtubular rootlets from the basal bodies form bundles passing into the cytoplasm, and microtubular and/or striated roots (text with tooltip) Striated roots (also called kinetodesma, banded roots, kinetodesmal fibers, or striated fibers) are banded flagellar roots that elaborate from basal bodies. They form a distinctive and diagnostic network in the Ciliata. connect the basal bodies to the nucleus thus forming a karyomastigont unit (text with tooltip) A karyomastigont is a 'unit' that includes basal bodies, flagellar roots, and a nucleus. .
    • Cell Covering: Naked but pellicular (text with tooltip) A pellicle is a complex outer cellular covering that occurs within the bounds of the plasmalemma. Often synonymous with the term theca, a pellicle defines such groups as the euglenoid-kinetoplastid clade amd the Kingdom Alveolatae. microtubules may be present.
    • Chloroplasts: Not present.
    • Food Reserves: Glycogen (text with tooltip) Glycogen is a branched-chain polysaccharide that occurs in an array of protists, some plant, some animals (including vertebrates) as a storage molecule. Formerly, glycogen was called amylum or animal starch. .
    • Mitochondria: Usually not present. When present, mitochondria do not have cristae (text with tooltip) Cristae (crista, sing.) generally refer to folds of the inner membranes of mitochondria. . May possess hydrogenosomes (text with tooltip) Hydrogenosomes are symbiotic bacteria or organelles that generate hydrogen as a kind of anaerobic mitochondrion. , likely mitochondria that are modified for anaerobic conditions.
    • 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 but not attached to a parabasal band (text with tooltip) Basal bodies are parallel when their orientation relative to each other is parallel. (as in parabasalids).
    • Nucleus: Connected to basal bodies via basal body roots to form a karyomastigont unit; Four flagellar basal bodies associated with a nucleus.
    • Centrioles: Not reported.
    • Inclusions and Ejectile Organelles:Food vacuoles.
  • B. Mitosis, Meiosis and Life History
    • MITOSIS: Intranuclear spindle (text with tooltip) An intranuclear spindle elaborates within the nuclear membrane of an organism with closed mitosis. .
    • MEIOSIS: Presumed.
    • SEXUAL REPRODUCTION AND LIFE HISTORY: Reported in some.
  • C. Ecology: Mostly endobiotic (text with tooltip) Endobiotic (adj.) means 'living within'. This refers to endosymbionts. and phagotrophic (text with tooltip) Phagotrophic (adj.) refers to a cell (or organism) that engulfs food particles. .
LITERATURE CITED

Baldauf, S. L. 2003a. The deep roots of eukaryotes. Science. 300 (5626): 1701-1703.

Brugerolle, G., and J. P. Mignot. 1990. Retortamonadida. 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. 259-265.

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

Cavalier-Smith, T. 2003b. The excavate protozoan phyla Metamonada Grasse emend. (Anaeromonadea, Parabasalia, Carpediemonas, Eopharyngia) and Loukozoa emend. (Jakobea, Malawimonas): their evolutionary affinities and new higher taxa. International Journal of Systematic and Evolutionary Microbiology. 53:1741-1758.

Dyer, B. D. 1990c. Parabasalia. 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. 252-258.

Grell, K. G. 1973. Protozoology. Springer-Verlag. New York.

Kudo, R.R. 1966. Protozoology. 5th ed. Charles C. Thomas Publisher. Springfield.

Lee, J. J. 1985. Order Retortamonadida. In: Lee, J.J., S.H. Hunter, and E.C. Bovee, eds. An Illustrated Guide to the Protozoa. Allen Press. Lawrence, Kansas. pp. 118-119.

Margulis, L. and K. Schwartz. 1988. Five kingdoms, an illustrated guide to the phyla of life on earth. 2nd Edition. W.H. Freeman and Co. New York.

Margulis, L. and K. Schwartz. 1998. Five kingdoms, an illustrated guide to the phyla of life on earth. 3rd Edition. W. H. Freeman and Company. New York.

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.

Patterson, D. J. 1999. The diversity of eukaryotes. American Naturalist. 154 (Suppl.): S96–S124.,

Simpson, A. G. B. 2003. Cytoskeletal organization, phylogenetic affinities and systematics in the contentious taxon Excavata (Eukaryota). International Journal of Systematic and Evolutionary Microbiology. 53: 1759-1777.

Sleigh, M.A., J.D. Dodge and D.J. Patterson. 1984. Kingdom Protista. In: Barnes, R.K.S., ed. A Synoptic Classification of Living Organisms. Sinauer Associates, Inc. Sunderland, Mass.

Taylor, F.J.R. 1976. Flagellate Phylogeny: A Study in Conflicts. J. Protozool. 23: 28-40. [C,L]

Taylor, F. J. R. 1999. Ultrastructure as a control for protistan molecular phylogeny. The American Naturalist. 154(supplement): S125-S136.

Tudge, C. 2000. The Variety of Life, A Survey and a Celebration of all the Creatures That Have Ever Lived. Oxford University Press. New York. [C,L]

Vickerman, K. 1990a. Diplomonadida. 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. 200-210.
By Jack R. Holt. Last revised: 02/12/2012
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