Cyclopyxis intermedia

Genus Cyclopyxis (Deflandre, 1929)

Diagnosis: Shell brown; in ventral view circular, in lateral view hemispherical; composed of agglutinated mineral particles; aperture central, invaginated, circular, sometimes with internal tube; few species with irregular or lobed pseudostome, margin never with thick organic lip but often with small mineral particles. Ventral surface usually smooth, dorsal part rough with larger sand grains.
More than 30 species and twice as many varieties. Type species: Cyclopyxis arcelloides (Penard, 1 902)

Ecology: sphagnum mosses, soil.

Common species:

Cyclopyxis eurystoma
Cyclopyxis kahli
Cyclopyxis intermedia

Key to the species:

1
Pseudostome star-shaped
2
1′
Pseudostome circular
3
1”
Pseudostome cross-shaped
C. crucistoma
2
Diameter of the test 335-400 microns
C. stellata
2′
Diameter of the test 120-130 microns
С. grospietschi
3
Diameter of the test < 80 microns
4
3′
Diameter of the test > 100 microns
9
4
Test completely covered with diatoms
C. bacillifera
4′
Test covered with quartz particles
5
5
Test flattened, height/diam. ratio < 0.55
6
5′
Test hemispherical (height/diam. > 0.55)
7
5”
Test conical
C. tronconica
6
Diameter of pseudostome > 0.65 diameter of the test
C. plana
6′
Diameter of pseudostome is 0.5-0.6 diameter of the test
C. amplecta
6”
Diameter of pseudostome < 0.5 diameter of the test
C. plana microstoma
7
Height of test equal or larger than diameter
8
7′
Height of test less than its diameter
C. eurystoma
8
Pseudostome slightly concave
C. eurystoma alta
8′
Pseudostome strongly concave
C. eurystoma sinuosa
9
Test hemispherical, pseudostome relatively large, > 1/3 test diameter
10
9′
Lateral sides of the test almost parallel; dorsal side in lateral view somewhat flattened, with large mineral particles often protruding from its sides; small mineral particles around the deep mouth
C. kahli
10
Test flattened
11
10′
Pseudostome circular
13
11
The diameter of the mouth is about half the diameter of the shell
12
11′
Diameter of mouth is not more than 1/4 of the diameter of the shell
C. aplanata microstoma
12
Diameter of the test 180-210 microns
С. aplanata
12′
Diameter of the shell 130 microns ave
C. eurystoma sinuosa
13
Diameter of the test 80-110 microns; pseudostome up to 1/2 the diameter of the test; surrounded by small, often shiny mineral particles, why it seems finely toothed
C. arcelloides
13’
Diameter of the test 330-380 microns; pseudostome > 1/2 of test diameter
C. penardi
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