Centropyxis orbicularis, in side view (left) and ventral view, 84 µm in diameter



Centropyxis orbicularis Deflandre, 1929


Diagnosis: shell in lateral view hemispherical, in dorsal view nearly circular;  shell usually build of numerous small quartz particles, sometimes mixed or replaced with small diatoms, embedded in a layer of organic cement; shell light grey or brown yellow, depending upon the density of the embedded xenosomes; xenosomes sometimes absent; aperture nearly semicircular, often with some larger quartz particles along the border.


Dimensions: Deflandre (1929) and Bonnet and Thomas (1960): 100-140 µm for the diameter and 70 and 50-95 um for the depth, respectively. My measurements: 59-160 µm.


Remarks: Very dark specimens are easily overlooked between debris.



After Deflandre (1929)
Centropyxis orbicularis
Centropyxis orbicularis
Shell in side view, 100 µm in diameter and Same shell in dorsal view
Shell c. 160 µm, moss, Germany