Rhizamoeba sp. (new species)

Rhizamoeba sp. 1-3, 13-15: cell in non-directed movement; 4-11: succesive stages from non-directed movement to locomotion; 12: resting cell.
Scale bar: 20 mkm

Rhizamoeba sp. 1-3:resting cell on agar; 3-9: successive views of a single cell. Scale bar: 20 mkm.

Rhizamoeba sp. 1-3: nuclei; 4: nucleolus. Scale bar 500 nm.

Rhizamoeba sp. 1: mitochondria; 2: cell surface; 3: dictyosome; 4-7: three different morphotypes of intracellular bacteria. Scale bar 500 nm.

Locomotive form monopodial, with well-pronounced hyaline cap. Adhesive uroid or bulbous uroid with several adhesive filaments. In non-directed movement the cell can form several pseudopodia Length of the locomotive form 80-140 mkm; breadth 10-25 mkm; L/B 6 - 9.

Resting cell has irregular, sometimes cometa-like shape. Usualy it is close with detritus and other small particles. Most of cells have one oblong nucleus with 2-3 tightly packed endosomal patches. Length of the nucleus is 8-10 mkm; breadth 4-5 mkm. Length of the endosome (all patches together) is 4-6 mkm. Some specimens containe up to 6 nuclei.

One contractile vacuole, which is usually situated in the posterior part of the amoeba body. The most common inclusions in the cytoplasm are small, dark, optically opaque granules, small food vacuoles. We never observed crystals in the cytoplasm of amoebae. Cysts are unknown.

Cell coat very thin, amorphous. Nucleoli are loose, with numerous channels. Up to 3 nuclei with similar nucleolar structure were seen in one section. Mitochondria have tubular cristae and transparent matrix. Dictyosomes consist of 3-5 cisternae. Three different types of intracellular bacteria were seen in the cells; all may present in one cell.

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