Pseudodifflugia virescens

Pseudodifflugia virescens

 

 

Genus Pseudodifflugia Schlumberger, 1845

 

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 à têt brun-bleuâtre, encroûté et comme recouvert de petits grains de sable, ovoïde, plus ou moins allongé ou raccourci; expansions filiformes très longues." (= 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:

 

1

Shell compressed

P. compressa

-

Shell not compressed

2

2

Shell < 25 µm

3

-

Shell > 30 µm

5

3

Aperture very small, c. 4-5 µm

P. microstoma
-

Aperture larger

4

4

Shell ovoid, without a neck

P. klarae

-

Shell ovoid, tapering to a small distinct neck

P. spec.
5

Shell densely covered with xenosomes

6
-

Shell loosely covered with xenosomes

P. fascicularis

6

Plasmabody fills the shell completely

P. archeri

-

Plasmabody doesn't fill the cell completely

P. virescens