Pyxidicula
Pyxidicula patens – 39 µm

 

Genus Pyxidicula Ehrenberg, 1938

Diagnosis: shell patelliform or hemispherical, more or less rigid, transparent, speckled; aperture circular, almost the entire diameter of test, or somewhat contracted by an inward margin; a single nucleus; one or more contractile vacuoles.

 

1Shell hemispherical2
Shell flattened, like a disc4
2Aperture with a narrow recurved marginP. operculata
Aperture with two narrow margins or collars, one curved inwards, the other curved outwards3
3Outer collar broader than the inner rim, hyaline, thinner than the rest of the shell and somewhat undulatedP. patens
Both collars relatively small with the same structure and color as the rest of the shell, not undulatedPyxidicula spec.
4Shell with a flat marginP. cymbalum
Shell with a hollow or tube shaped marginP. invisitata

 

Pyxidicula operculata
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