Arcella rotundata
Arcella rotundata, 42 µm

Arcella rotundata Playfair, 1918

Diagnosis: shell with a depressed dome in side-view, expanded at the sides above the baseline; no basal angles, the margin of the dome merging into the base in a single, broadly rounded curve.

Dimensions: literature: diameter 47-62 µm, height 25-30 µm.

Remarks: In a recent study Lahr and Lopes (2009) showed that Arcella hemisphaerica and A. rotundata are indistinguishable. They consider both species as a single entity. See Arcella hemisphaerica Perty, 1852.
The main feature that could separate individuals of A. rotundata from those of A. hemisphaerica is the larger semi-circle contour in lateral view, but this could also fall within the natural variation. Further observations and measurements are needed.

Arcella rotundata
Arcella rotundata
Arcella rotundata, 47 µm – Austria, Tirol
Recent posts

Microcorycia spec. 4

Microcorycia spec. , folded Microcorycia spec.? I found this specimen in a sample from moss on a fallen tree in a marsh in the Naardermeer,

Read More »

Microchlamys spec.

Microchlamys spec., the same cell in lateral view Microchlamys spec. Diagnosis: Shell relatively high compared with all described species. The diameter is twice the height.

Read More »

Excentrostoma

Infraorder Excentrostoma Kosakyan et al., 2016   Diagnosis: Testate amoebae with an eccentrically placed aperture; test organic with few or many xenosomes. Family Centropyxidae Jung, 1942  

Read More »

Longithecina

Infraorder Longithecina Kosakyan et al., 2016   Diagnosis: Testate amoebae with a more or less tubular or cylindrical test and a terminal aperture; test with

Read More »