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Family Amoebidae Ehrenberg, 1838

Diagnosis: Locomotive amoebae usually greater than 80 µm in length, with cylindrical pseudopodia with hyaline caps. Some species monopodial but most polypodial. Many have cytoplasmic crystals. Nucleus often with nuclear material in small fragments.

Key to the genera of family Amoebidae

1 Amoeba multinucleate

2

Amoeba usually with one nucleus

3

2 Amoeba usually polypodial, with longitudinal ridges

Chaos

Amoeba usually monopodial, without longitudinal ridges

Parachaos

3 Amoeba monopodial, only branched when changing direction

4

Amoeba usually polypodial

5

4 Amoeba free-living

Trichamoeba

Amoeba parasitic on freshwater coelenterates (hydra)

Hydramoeba

5 One dominant leading pseudopodium with smaller lateral pseudopodia

6

Pseudopodia more or less equal-sized, radiating from a central mass like the fingers of a hand; villous bulb uroid

Polychaos

6 Amoeba usually > 200 µm; nucleus granular

7

Amoeba usually < 200 µm; nucleus with few nucleolar pieces

Deuteramoeba

7 With longitudinal ridges

Amoeba

Without longitudinal ridges

Metachaos

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