Rhizamoeba coerulea
Rhizamoeba coerulea, about 130 µm large, with at least two nuclei, one elongated oval and the other one more spherical.

 

 

Rhizamoeba coerulea (Schaeffer, 1926) Siemensma, 1987

 

Diagnose: Medium-sized to large amoeba, which can spread very flat with  very fine subpseudopodia, sticked to the substrate;  polypodial form usually covered with detritus; monopodial form bat-shaped; numerous, up to 32 small nuclei; cytoplasm clear, with many very small granules and some elliptical crystals; several contractile vacuoles; hyaloplasm at the anterior end with eruptive bulges; hyaloplasm may run back along the sides.

 

Dimensions: my measurements 150-260 µm, nuclei 4.8-24.0 µm (Penard 5-7 µm); Schaeffer (1926) 150 µm.

 

Ecology: Fresh water. I found this species in a stream near Epe (1980) and in a pond at Groeneveld (2012), both in the Netherlands. All amoebae were collected from floating detritus.

 

Remarks: It is possible that this species is identical with R. clavarioides.

 

Rhizamoeba coerulea
Rhizamoeba species are very sensitive for light. This one started to retract its pseudopodia immediately when it came into the light path of the microscope.
Rhizamoeba coerulea
Rhizamoeba coerulea
Nuclei, 15 µm and 11 µm, each with two peripheral nucleoli.
Rhizamoeba coerulea
The same cell as above after two weeks in a moisture chamber. It is also retracting its pseudopodia.
Rhizamoeba coerulea
Rhizamoeba caerulea, 130 µm
Rhizamoeba coerulea
Rhizamoeba caerulea
Rhizamoeba caerulea A-B: polypodia; C-D transition from polypodium to monopodium; E: monopodium; F: floating form. After Siemensma, 1987.
Rhizamoeba coerulea
Rhizamoeba caerulea A-C: monopodia; D: flattened form on agar; E-G: development of pseudopodia; nuclei, drawn in their internal relationship.- After Siemensma, 1987