world of amoeboid organisms

Key to Centropyxis species
1Test in dorsal view circular or almost circular2
Test in dorsal view irregular due to various outgrows and invaginations22
Test in dorsal view elliptical or ovoid or resembling an 823
2Test with spines3
Test without spines14
3Edges of pseudostome with bridges or pilars between edge and dorsal part4
Bridges absent7
4Diameter of the test 140-160 μm, in lateral view hemisphericalCentropyxis hemispherica
C. hemisphaerica
Diameter of the test does not exceed 100 μm5
5Test in lateral view resembling a cap6
Test in lateral view in the form of a triangleCentropyxis decloitri
C. decloitri
6 Spines along the entire fundusCentropyxis hirsuta
C. hirsuta
Spines only on the edge of the fundusCentropyxis cassis spinifera
C. cassis spinifera
7Pseudostome slightly eccentric8
Pseudostome strongly eccentric9
8Test 130 – 320 μmCentropyxis discoides
C. discoides
Test < 60 μmCentropyxis delicatula
C. delicatula
9Pseudostome lobedCentropyxis spinosa
C. spinosa
Pseudostome not lobed, sometimes irregular in shape10
10Aperture lobed or crenateCentropyxis aculeata dentistoma
C. aculeata dentistoma
Aperture not lobed or crenate11
11Spines very long, located not only on the fundus, but also on the visorCentropyxis discoides solari
C. discoides solari
Spines only located on the fundus12
12Spines very long (40-60 μm)Centropyxis tropica
C. aculeata tropica
Spines shorter13
13Diameter of the test 110-160 μmCentropyxis aculeata
C. aculeata
Diameter of the test 170-200 μmCentropyxis aculeata grandis
C. aculeata grandis
Diameter of the test 80-90 μmCentropyxis aculeata minima
C. aculeata minima
14Test in lateral view flattened, rarely hemispherical15
Test in lateral view semi circular or slightly smaller or larger than hemispherical16
15Test > 150 μmCentropyxis ecornis
C. ecornis
Test < 60 μmCentropyxis delicatula
C. delicatula
16Pseudostome very large (about half the diameter of the test), jaggedCentropyxis latior
C. latior
Pseudostome not so big, its edge is not jagged17
17Test with internal bridgesCentropyxis laevigata
C. laevigata
Bridges absent18
18Pseudostome slightly eccentric19
Pseudostome strongly eccentric20
19Diameter of the test 140-170 μmCentropyxis austriaca
C. austriaca
Diameter of test < 80 μmCentropyxis minuta
C. minuta
20Pseudostome small, close to the edge of the anterior part of the testC. plagiostoma
Pseudostome larger, halfway between center and edge21
21Diameter of test 100-140 μmCentropyxis orbicularis
C. orbicularis
Diameter of test < 70 μmCentropyxis aerophila sphagnicola
C. aerophila sphagnicola
22Test in lateral view broad, pseudostome circular or elliptical, small, located on the ventral side of the testCentropyxis aurita
C. aurita
Test elongated elliptical in dorsal view, pseudostome crenate, subterminal, located at an angle of 45° to the longitudinal axis of the testCentropyxis chardeziella
C. chardeziella
23Test in lateral view similar in shape to the figure-eight by narrowing between the pseudostome and fundus24
Test in dorsal view elliptical or ovate30
24Pseudostome subterminal, located at an angle of 30° with respect to the longitudinal axis of the testCentropyxis loffleri
C. loffleri
Pseudostome located on the ventral side of the test325
25Test without spines26
Test with spines27
26Main part of the test a perfect sphere with an aperture, forming a kind of diaphragm between pseudostome and test bodyConicocassis pontigulasiformis
Conicocassis pontigulasiformis
Main part of the test without diaphragmaCentropyxis platystoma
C. platystoma
27Test in lateral view flattened, pseudostome located near the center of the ventral side; length of test 160-170 μmCentropyxis mirabilis
C. mirabilis
Test in lateral view high, at least in the fundus, pseudostome very eccentric, length of test < 120 μm28
28Many spines, arranged randomly; visor turned outwards29
One spine, long; visor not turned outwardsCentropyxis platystoma armata
C. platystoma armata
29Length of test 70-80 μmCentropyxis grelli
C. grelli
Length of test 140-200 μmCentropyxis adami
C. adami
30Posterior part in lateral view strongly curved inwards, forming a perforated diaphragm, separating the visor from the fundus31
Test without a perforated diaphragm32
31Length of test 65-100 μmCentropyxis sylvatica
C. sylvatica
Length of test 35-45 μmC. sylvatica minor
32Pseudostome narrow sickle-shaped, test in dorsal view ovoid
= Heleopera???
Centropyxis declivistoma
C. declivistoma
Pseudostome circular or elliptical33
33Test in lateral view high, height of the test is equal, slightly less or exceeds the width34
Test in lateral view more flattened, height less than width43
34Height of the test considerably exceeds the width and lengthCentropyxis deflandrei
C. deflandrei
Height of the test approximately equal to the width of the test.35
35Test with spines36
Test without spines38
36One spine, thick, hollow, located on the extension of the longitudinal axis of the testCentropyxis chardezi
C. chardezi
Spines a lot, are located throughout the fundus37
37Length of test 90-120 μmCentropyxis gibba
C. gibba
Length of test 60-75 μmCentropyxis notonyx
C. notonyx
38Test length >110 μm39
Test length < 90 μm40
39Visor very wide, resembling the edge of a hatCentropyxis cordobensis
C. cordobensis
Visor not so large, formed by very large grains of sandCentropyxis janetscheki
C. janetscheki
40Pseudostome subterminal, located at an angle of 45 ° to the longitudinal axis of the testCentropyxis sacciformis
C. sacciformis
Pseudostome located on the ventral side of the test41
41In lateral view test in pseudostomal area almost not narrowedCentropyxis villiersi
C. villiersi
In lateral view test in pseudostomal area narrowed42
42Height of the test slightly exceeds the widthC. gibba inermis
Height of the test is slightly smaller than the widthCentropyxis aerophila
C. aerophila
43Width of test exceeds the length44
The width of test does not exceed the length45
44Length of test 50-60 μmCentropyxis aculeata lata
C. aculeata lata
Length of test 150-205 μmCentropyxis compressa
C. compressa
45Pseudostome subterminal, located at an angle of 50-60 ° to the longitudinal axis of the test46
Pseudostome ventrally located47
46Thorns 1-6, elongated testCentropyxis marsupiformis
C. marsupiformis
Spines 4-8, test widerCentropyxis marsupiformis obesa
C. marsupiformis obesa

47Test with spines48
Test without spines53
48A wide flat keel is located along the perimeter of the test, the outgrowth of which forms spinesCentropyxis horrida
C. horrida
Keel is absent49
49Spines are located on both the abdomen and on the visorCentropyxis decloitrella
C. decloitrella
Spines only on the abdomen50
50Test in dorsal view trapezoidalCentropyxis pyriformis
C. pyriformis
Test dorsal view is oval, elliptical or ovate51
51There is a groove between the organic mouth area of the test and the posterior endC. percolahiensis
Furrow absent52
52Pseudostome circularCentropyxis aculeata
C. aculeata
Pseudostome ovalCentropyxis aculeata oblonga
C. aculeata oblonga
53Length of test < 100 μm54
Length of test > 100 μm55
54Test elongate elliptical in dorsal view; pseudostome circular or semicircular, large, occupies 1/3 part of the length of the testCentropyxis elongata
C. elongata
The test is broad-elliptical in dorsal view, pseudostome convex in the front, straightly cut from the rear; visor is lined with large xenosomesCentropyxis cassis
C. cassis

55Test with internal bridges56
Test without internal bridges57
56Ventral surface curved, pseudostome located almost at the centerCentropyxis kurakchayensis
C. kurakchayensis
Ventral surface flat, pseudostome eccentricallyCentropyxis gasparella
C. gasparella
57Length of test > 200 μm, there is a wide visor in the form of the fields of a hatCentropyxis recurvata
C. recurvata
Test smaller, visor not so wide58
58Pseudostome small, roundish, located at the bottom of a deep pre-oriental funnelCentropyxis invaginata
C. invaginata
Pseudostome larger59
59There is a groove between the organic aperture of the test and the xenosomes on the posterior endC. percolahiensis inermis
Groove absent, posterior end usually contains large sand grainsCentropyxis constricta
C. constricta

This key was published by Mazei and Tsyganov in 2006, Moskou, in Russian. I’ve translated it and modified it by adding some species.

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