Key to Centropyxis species


1 Test in lateral view flattened; ratio of test height/diameter 2
- Test in lateral view not flattened or high; height/diameter 0.40-0.88 22
- Test in lateral view high; height/diameter > 0.88) 23
2 Basal border located in the middle part of the test or the contour of the shell is denticulated 3
 - Basal border absent or located at the base of the test, the contour of the shell is smooth or wavy 14
3 Contour of the test is smooth 4
- Contour of the test denticulated 7
4 Test in dorsal view round

Centropyxis hemispherica

C. hemisphaerica

- the plan has the shape of an elongated hexagon 5
5 Dorsal surface of test trapezoidal 6
- Dorsal surface of shell round or conical

Centropyxis decloitri

C. decloitri

6 Test large (diameter of the test not less than 150 microns)

Centropyxis hirsuta

C. hirsuta

- Test of medium size (diameter of shell 70-130 μm)

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

Centropyxis delicatula







C. delicatula

9 Pseudostome lobed

Centropyxis spinosa

C. spinosa

- Pseudostome not lobed, sometimes irregular in shape 10
10 Aperture lobed or crenate

Centropyxis aculeata dentistoma

C. aculeata dentistoma

- Aperture not lobed or crenate 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

14 Test in lateral view flattened, rarely hemispherical 15
  Test in lateral view semi circular or slightly smaller or larger than hemispherical 16
15 Test > 150 μm

Centropyxis ecornis

C. ecornis

- Test < 60 μm

Centropyxis delicatula







C. delicatula

16 Pseudostome very large (about half the diameter of the test), jagged

Centropyxis latior

C. latior

- Pseudostome not so big, its edge is not jagged 17
17 Test with internal bridges

Centropyxis laevigata

C. laevigata

- Bridges absent 18
18 Pseudostome slightly eccentric 19
- Pseudostome strongly eccentric 20
19 Diameter of the test 140-170 μm

Centropyxis austriaca

C. austriaca

- Diameter of test < 80 μm

Centropyxis minuta

C. minuta

20 Pseudostome small, close to the edge of the anterior part of the test







C. plagiostoma

  Pseudostome larger, halfway between center and edge 21
21 Diameter of test 100-140 μm

Centropyxis orbicularis

C. orbicularis

- Diameter of test < 70 μm

Centropyxis aerophila sphagnicola

C. aerophila sphagnicola

22 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

23 Test in lateral view similar in shape to the figure-eight by narrowing between the pseudostome and fundus 24
- Test in dorsal view elliptical or ovate 30
24 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 25
25 Test without spines 26
- Test with spines 27
26 Main part of the test a perfect sphere with an aperture, forming a kind of diaphragm between pseudostome and test body

Centropyxis pontigulasiformis








C. pontigulasiformis

- Main part of the test without diaphragma 

Centropyxis platystoma

C. platystoma

27 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 28
28 Many spines, arranged randomly; visor turned outwards 29
  One spine, long; visor not turned outwards

Centropyxis platystoma armata

C. platystoma armata

29 Length of test 70-80 μm

Centropyxis grelli

C. grelli

  Length of test 140-200 μm

Centropyxis adami

C. adami

30 Posterior part in lateral view strongly curved inwards, forming a perforated diaphragm, separating the visor from the fundus 31
- Test without a perforated diaphragm 32
31 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 33
33 Test in lateral view high, height of the test is equal, slightly less or exceeds the width 34
- Test in lateral view more flattened, height less than width 43
34 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. 35
35 Test with spines 36
- Test without spines 38
36 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 37
37 Length of test 90-120 μm

Centropyxis gibba

C. gibba

- Length of test 60-75 μm

Centropyxis notonyx

C. notonyx

38 Test length >110 μm 39
- Test length < 90 μm 40
39 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

40 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 41
41 In lateral view test in pseudostomal area almost not narrowed

Centropyxis villiersi

C. villiersi

- In lateral view test in pseudostomal area narrowed 42
42 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

43 Width of test exceeds the length 44
- The width of test does not exceed the length 45
44 Length of test 50-60 μm

Centropyxis aculeata lata

C. aculeata lata

- Length of test 150-205 μm

Centropyxis compressa

C. compressa

45 Pseudostome subterminal, located at an angle of 50-60 ° to the longitudinal axis of the test 46
- Pseudostome ventrally located 47
46 Thorns 1-6, elongated test

Centropyxis marsupiformis

C. marsupiformis

- Spines 4-8, test wider

Centropyxis marsupiformis obesa

C. marsupiformis obesa

47 Test with spines 48
- Test without spines 53
48 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 49
49 Spines are located on both the abdomen and on the visor

Centropyxis decloitrella

C. decloitrella

- Spines only on the abdomen 50
50 Test in dorsal view trapezoidal

Centropyxis pyriformis

C. pyriformis

- Test dorsal view is oval, elliptical or ovate 51
51 There is a groove between the organic mouth area of ​​the test and the posterior end C. percolahiensis
- Furrow absent 52
52 Pseudostome circular

Centropyxis aculeata

C. aculeata

- Pseudostome oval

Centropyxis aculeata oblonga

C. aculeata oblonga

53 Length of test < 100 μm 54
- Length of test > 100 μm 55
54 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

55 Test with internal bridges 56
- Test without internal bridges 57
56 Ventral surface curved, pseudostome located almost at the center

Centropyxis kurakchayensis

C. kurakchayensis

- Ventral surface flat, pseudostome eccentrically

Centropyxis gasparella

C. gasparella

57 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 58
58 Pseudostome small, roundish, located at the bottom of a deep pre-oriental funnel

Centropyxis invaginata

C. invaginata

- Pseudostome larger 59
59 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.