Key to Centropyxis species


1 Test in dorsal view circular or almost circular 2
- Test in dorsal view elliptical or ovoid or resembling an 8 21
- Test in dorsal view irregular, with outgrowths and invaginations 20
2 Test with spines 3
 - Test without spines 13
3 Test without internal bridges 4
- Test with internal bridges 7
4 Diameter of test 140-160 μm, in lateral view hemispherical

Centropyxis hemispherica

C. hemisphaerica

- Diameter of test < 100 μm 5
5 Test in lateral view resembling a cap 6
- Test in lateral view resembling a triangle

Centropyxis decloitri

C. decloitri

6 Spines along the entire fundus

Centropyxis hirsuta

C. hirsuta

- Spines only on the edge of the fundus

Centropyxis cassis spinifera

C. cassis spinifera

7 Pseudostome slightly eccentric 8
  Pseudostome strongly eccentric 9
8 Test 130 - 320 μm

Centropyxis discoides

C. discoides

  Test < 60 μm C. delicatula
9 Pseudostome lobed

Centropyxis spinosa

C. spinosa

- Pseudostome not lobed, sometimes irregular in shape 10
10 Spines notched

Centropyxis aculeata dentistoma

C. aculeata dentistoma

- Aperture not crenate1 11
11 Spines very long, located not only on the fundus, but also on the visor

Centropyxis discoides solari

C. discoides solari

- Spines only located on the fundus 12
12 Spines very long (40-60 μm)

Centropyxis tropica

C. aculeata tropica

- Spines shorter 13
13 Diameter of the test 110-160 μm

Centropyxis aculeata

C. aculeata

- Diameter of the test 170-200 μm

Centropyxis aculeata grandis

C. aculeata grandis

- Diameter of the test 80-90 μm

Centropyxis aculeata minima

C. aculeata minima

13 Test in lateral view flattened, rarely hemispherical 14
  Test in lateral view semi circular or slightly smaller or larger than hemispherical 15
14 Test > 150 μm

Centropyxis ecornis

C. ecornis

  Test < 60 μm C. delicatula
-   15
15 Pseudostome very large (about half the diameter of the test), jagged

Centropyxis latior

C. latior

- Pseudostome not so big, its edge is not jagged 16
16 Test with internal bridges

Centropyxis laevigata

C. laevigata

- Bridges absent 17
17 Pseudostome slightly eccentric 18
- Pseudostome strongly eccentric 19
18 Diameter of the test 140-170 μm

Centropyxis austriaca

C. austriaca

- Diameter of test < 80 μm

Centropyxis minuta

C. minuta

19 Pseudostome small, close to the edge of the anterior part of the test C. plagiostoma
  Pseudostome larger, halfway between center and edge 20
20 Diameter of test 100-140 μm

Centropyxis orbicularis

C. orbicularis

- Diameter of test < 70 μm

Centropyxis aerophila sphagnicola

C. aerophila sphagnicola

21 Test in lateral view broad, pseudostome circular or elliptical, small, located on the ventral side of the test

Centropyxis aurita

C. aurita

- Test elongated elliptical in dorsal view, pseudostome crenate, subterminal, located at an angle of 45° to the longitudinal axis of the test

Centropyxis chardeziella

C. chardeziella

22 Test in lateral view similar in shape to the figure-eight by narrowing between the pseudostome and fundus3 23
- Test in dorsal view elliptical or ovate 28
23 Pseudostome subterminal, located at an angle of 30° with respect to the longitudinal axis of the test

Centropyxis loffleri

C. loffleri

- Pseudostome located on the ventral side of the test3 24
24 Test without spines 25
- Test with spines 26
25 Main part of the test a perfect sphere with an aperture, forming a kind of diaphragm between pseudostome and test body


C. pontigulasiformis

- Main part of the test without diaphragma 

Centropyxis platystoma

C. platystoma

26 Test in lateral view flattened, pseudostome located near the center of the ventral side; length of test 160-170 μm

Centropyxis mirabilis

C. mirabilis

  Test in lateral view high, at least in the fundus, pseudostome very eccentric, length of test < 120 μm 27
27 Many spines, arranged randomly; visor turned outwards 28
  One spine, long; visor not turned outwards

Centropyxis platystoma armata

C. platystoma armata

28 Length of test 70-80 μm

Centropyxis grelli

C. grelli

  Length of test 140-200 μm

Centropyxis adami

C. adami

29 Posterior part in lateral view strongly curved inwards, forming a perforated diaphragm, separating the visor from the fundus 30
- Test without a perforated diaphragm 37
30 Length of test 65-100 μm

Centropyxis sylvatica

C. sylvatica

- Length of test 35-45 μm C. sylvatica minor

Pseudostome narrow sickle-shaped, test in dorsal view ovoid

= Heleopera???

Centropyxis declivistoma

C. declivistoma

- Pseudostome circular or elliptical 32
32 Test in lateral view high, height of the test is equal, slightly less or exceeds the width 33
- Test in lateral view more flattened, height less than width 42
33 Height of the test considerably exceeds the width and length

Centropyxis deflandrei

C. deflandrei

- Height of the test approximately equal to the width of the test. 34
34 Test with spines 35
- Test without spines 37
35 One spine, thick, hollow, located on the extension of the longitudinal axis of the test

Centropyxis chardezi

C. chardezi

- Spines a lot, are located throughout the fundus 35
36 Length of test 90-120 μm

Centropyxis gibba

C. gibba

- Length of test 60-75 μm

Centropyxis notonyx

C. notonyx

37 Test length >110 μm 38
- Test length < 90 μm 39
38 Visor very wide, resembling the edge of a hat

Centropyxis cordobensis

C. cordobensis

- Visor not so large, formed by very large grains of sand

Centropyxis janetscheki

C. janetscheki

39 Pseudostome subterminal, located at an angle of 45 ° to the longitudinal axis of the test

Centropyxis sacciformis

C. sacciformis

- Pseudostome located on the ventral side of the test 40
40 In lateral view test in pseudostomal area almost not narrowed

Centropyxis villiersi

C. villiersi

- In lateral view test in pseudostomal area narrowed 41
41 Height of the test slightly exceeds the width C. gibba inermis
- Height of the test is slightly smaller than the width

Centropyxis aerophila

C. aerophila

42 Width of test exceeds the length 43
- The width of test does not exceed the length 44
43 Length of test 50-60 μm

Centropyxis aculeata lata

C. aculeata lata

- Length of test 150-205 μm

Centropyxis compressa

C. compressa

44 Pseudostome subterminal, located at an angle of 45 ° to the longitudinal axis of the test 45
- Pseudostome ventrally located 46
45 Thorns 1-3, elongated test

Centropyxis marsupiformis

C. marsupiformis

- Spines 4-8, test wider

Centropyxis marsupiformis obesa

C. marsupiformis obesa

46 Test with spines 47
- Test without spines 52
47 A wide flat keel is located along the perimeter of the test, the outgrowth of which forms spines

Centropyxis horrida

C. horrida

- Keel is absent 48
48 Spines are located on both the abdomen and on the visor

Centropyxis decloitrella

C. decloitrella

- Spines only on the abdomen 49
49 Test in dorsal view trapezoidal

Centropyxis pyriformis

C. pyriformis

- Test dorsal view is oval, elliptical or ovate 50
50 There is a groove between the organic mouth area of ​​the test and the posterior end C. percolahiensis
- Furrow absent 51
51 Pseudostome circular

Centropyxis aculeata

C. aculeata

- Pseudostome oval

Centropyxis aculeata oblonga

C. aculeata oblonga

52 Length of test < 100 μm 53
- Length of test > 100 μm 54
53 Test elongate elliptical in dorsal view; pseudostome circular or semicircular, large, occupies 1/3 part of the length of the test

Centropyxis 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 xenosomes

Centropyxis cassis

C. cassis

54 Test with internal bridges 55
- Test without internal bridges 56
55 Ventral surface curved, pseudostome located almost at the center

Centropyxis kurakchayensis

C. kurakchayensis

- Ventral surface flat, pseudostome eccentrically

Centropyxis gasparella

C. gasparella

56 Length of test > 200 μm, there is a wide visor in the form of the fields of a hat

Centropyxis recurvata

C. recurvata

- Test smaller, visor not so wide 56
57 Pseudostome small, roundish, located at the bottom of a deep pre-oriental funnel

Centropyxis invaginata

C. invaginata

- Pseudostome larger 58
58 There is a groove between the organic aperture of the test and the xenosomes on the posterior end C. percolahiensis inermis
- Groove absent, posterior end usually contains large sand grains

Centropyxis 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.