Genus Polychaos Schaeffer, 1926


Diagnosis: during active locomotion usually polypodial, palmate, with several tubular pseudopodia, more or less equal and with no one dominant, proceeding anteriorly and anterior-laterally from common posterior mass; posterior of cell often with a bundle of fused, remnant pseudopodia; pseudopodia sometimes flattened and broadening towards ends; monopodial in rapid locomotion with a bulbous uroid; no dorsal ridges; nucleus granular or with other arrangements of nucleolar material; crystals irregular or plate-like to bi-pyramidal, some as paired bodies or clusters.


Key to the species:  

1 Nucleus with a ring- or belt-shaped nucleolus



Nucleus granular



Nucleolar material in few narrow peripheral lobes, sometimes in a single curved band, twisting inside the nucleus.

P. fasciculatum

Nucleolar material forming a perforated sphere inside the nucleus.

P. annulatum


Nucleus discoid, spheroid or ovoid

P. dubium

- Nucleus shallowly to deeply cup-shaped

P. nitidubium



Polychaos annulatum
Polychaos fasciculatum