Microworld

world of amoeboid organisms

Centropyxis constricta
C. constricta, a,b after Ehrenberg, 1841, c 1843

Centropyxis constricta (Ehrenberg, 1841) Penard, 1890
Basionym: Arcella constricta Ehrenberg, 1841

Diagnosis: Shell of medium size, very variable in size and shape, elliptical or sometimes broad ovoid in front view, more or less flattened; aperture at the border of the shell, eccentric, largely elliptic or nearly circular, deeply invaginated; shell covered with closely-set sand grains and/or diatoms, giving a grey color to the test; fundus sometimes with some larger mineral grains.

Dimensions: Literature 90-150 µm, my measurements 70-130 µm.

Ecology: Freshwater, mosses and Sphagnum.

Remarks: Ehrenberg (1841) gives following description: A constricta, ovata, apertura maxima marginali ibique leviter constricta. Multas vidi. Icon! (translated: oval, the largest marginal opening! and there slightly constricted. I have seen many. Icon!).
Both Penard (1902) and Deflandre (1929) complained about the difficulty of distinguishing this species from other species. Deflandre has made an attempt to re-describe this species, but for me without desired results. Penard already described this species as highly variable.

Centropyxis constricta Penard
Population from a fen in Mongolia, 2023, length 70-100 µm.
Centropyxis constricta Penard
C. constricta, after Penard, 1902. Penard included C. platystoma in his description.
Centropyxis constricta Penard
C. constricta, after Deflandre, 1929
Centropyxis constricta
Centropyxis constricta
C. constricta, lateral view
The same shell in ventral view
Centropyxis constricta
Centropyxis constricta
C. constricta, lateral view
The same shell in ventral view
Centropyxis constricta
Centropyxis constricta
Centropyxis constricta
Centropyxis constricta
Centropyxis constricta side view
Centropyxis constricta
Centropyxis constricta
C. constricta, c. 60 µm, in ventral view and lateral view
Centropyxis constricta
Centropyxis constricta
Centropyxis constricta
Centropyxis constricta
Centropyxis constricta
Centropyxis constricta
Centropyxis constricta
Ferry Siemensma, created February 23, 2019; last modified January 29, 2024
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