Arcella costata
Arcella costata

 

 

Arcella costata Ehrenberg, 1847

 

Diagnosis: shell in side view trapezoid, with a flat polygonal top; slopes with six or more angular facets, bordered by some prominent folds; aperture slightly invaginated, circular and bordered by a collar.

 

Dimensions: in literature diameters 52-100 µm; my measurements: c. 90 µm.

 

Ecology: waterplants

 

Remarks: Variation in this species appears to be restricted to the arrangement of the angular folds. Specimens can be confused with Arcella conica, which has a domed top.

 

Arcella costata
Arcella costata, Peru, rainforest