Amoeba leningradensis Page & Kalinina, 1984
Diagnosis: Locomotive form often polypodial, with length approximately 160-550 µm, mean approximately 360 µm; hyaline cap less prominent as in A. proteus; nucleus a sphere which is often slightly compressed, often appearing ovoidal, with its greatest diameter 21 to 29 µm, mean 25 µm; many cytoplasmic crystals, mostly truncate bipyramids; uroid coarsely morulate or knobby and occasionally included the trailing remnants of pseudopodia which has passed to the posterior end.
Plasma membrane covered with amorphous coat 13-20 nm thick; nuclear envelope with internal fibrous lamina differentiated into hexagonal prisms, lamina usually 400 to 550 nm thick, inner diameter of each prism approximately 165 nm, nucleolar material concentrated around periphery of nucleus but also occurring in interior: golgi bodies composed of about four flattened saccules and associated vesicles, possibly sometimes of vesicles alone. Nucleus incompatible, by transplantation, with nucleus and cytoplasm of Amoeba proteus.
Known habitat: Fresh water, northwestern USSR and Florida, USA.
Remarks: I found three specimens of this species in a sample from a garden pond in Wellington, Florida. The material was kindly supplied to me by Sandra Redeker (2014). All specimens looked the same in their overall shape and behaviour, though one was twice as long (400 µm) as the smallest one (180 µm). The nucleus of the first specimen was ovoid, the other specimens had a checker shaped nucleus, resembling a proteus nucleus. The nuclei varied from 21-33 µm in diameter. The nucleolar material was scattered through the nucleus, but more concentrated around the periphery. All specimens never showed any dorsal folds or ridges. The uroid was finely papillated, a feature I have rarely seen with A. proteus.