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Diagnosis: Shell oval or pyriform, rigid test without collar, densely or sparsely agglutinated with mineral xenosomes;  xenosomes attached to the surface of the test, or embedded into and surrounded by a structureless, sheath like organic cement matrix; aperture may be circular and regularly ag­glutinated with xenosomes; it may have an organic rim, or it may be narrow and irregular; test not filled entirely by the cytoplasm; filopodia branching.

Type species: Pseudodifflugia gracilis Schlumberger, 1845.

Ecology: freshwater, soil and marine littoral sands.

Remarks: About 20 species, often with incomplete descriptions. Even the type species needs a much more accurate description: Animal test brown-bluish, encrusted and covered with small sand grains, ovoid, more or less elongated, with very long filipods”. That’s all, without any images.

Probably this genus is a “Sammelgruppe”, a taxon that contains a number of not closely related amoeboids. Some species may belong to the genus Plagiophrys, like P. compressa.

 

Key to some species:

1Shell compressed

P. compressa

Shell not compressed

2

2Shell < 25 µm

3

Shell > 30 µm

5

3Aperture very small, c. 4-5 µmP. microstoma
Aperture larger

4

4Shell ovoid, without a neck

P. klarae

Shell ovoid, tapering to a small distinct neckP. spec.
5Shell densely covered with xenosomes6
Shell loosely covered with xenosomes

P. fascicularis

6Plasmabody fills the shell completely

P. archeri

Plasmabody doesn’t fill the cell completely

P. virescens

Pseudodifflugia virescens
Pseudodifflugia virescens
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