Genus Metachaos Schaeffer, 1926
Diagnosis: Locomotive form usually between 75 and 500 µm in length, slender and fast moving; pseudopodia cylindrical and smooth with clear hyaline zone; cytoplasm often very granulated with bipiramidal and/or irregular crystals; nucleus discoid or spherical; uroid morulate and temporary. Distinguish from Polychaos.
Ecology: Freshwater and marine.
Type species: Metachaos discoides (Schaeffer, 1916)
Species: Metachaos spec.
The description of Schaeffer (1926) is:
“This genus, for which I propose the name Metachaos, comprises large amebas that move during locomotion by means of determinate pseudopods, that is, pseudopods that direct locomotion. The general shape of the body is oblong, resembling an antler or staghorn. The mass of the body is divided into blunt pseudopods which are cylindrical or sub-cylindrical in shape, without longitudinal folds, such as are observed in the genus Chaos. The granular endoplasm fills the entire ameba, or all but the extreme tips of the advancing pseudopods, and the granules are very evenly distributed, indicating a unified streaming of the endoplasm which involves the whole of the endoplasmic contents. A main pseudopod which leads in locomotion is distinguishable at all times. The whole ameba is therefore continually flowing through a single pseudopod, the main one, though it is always forming a number of others. Or, with a change of tense, the whole ameba will flow through the tip of its one main pseudopod. As the type species I designate the common discoides Schaeffer. The large laureata of Penard belongs in this genus.”