The identification of Trinema species living in Sphagnum and soils
Compiled from the following sources: (Grospietsch 1958; Harnisch 1958;
Luftenegger et al. 1988; Ogden & Hedley 1980).
Disclaimer. This is a grossly simplified key of some main types. The true diversity of
the genus is much higher both considering described taxa, and certainly even more so
if pseudo-cryptic and cryptic taxa are considered. Still imperfect as this document is
hopefully it will be useful. Any suggestions for improvement are very welcome!
Copyright Edward Mitchell 2002-. All material can be used freely for non-profit
educational purposes. An acknowledgement for such a use would be appreciated.
Key
1.
Breadth to length ratio > 0.55 (range 0.57-0.62). Oval aperture, surrounded by a
thick border: Ratio between the small diameter of aperture and the distance
from the top of aperture to the oral end of the test < 2.
2
Breadth to length ratio < 0.55 (range 0.41-0.51). Round aperture, surrounded by
a thin border: Ratio between the small diameter of aperture and the distance
from the top of aperture to the oral end of the test > 2.
3
2.
Shell composed of two independent parts. Outer component carries the circular
shell platelets, inner part forms the oval aperture. In side view the outline has
the shape of a smooth pointed egg with the two side converging symmetrically
towards the anterior end of the test. Aperture clearly invaginated. (Figure 1)
T. penardi
In side view the outline is not symmetric. The anterior end of the test is very
compressed, and the anterior lip of the aperture that creates a distinct thickening
on the outline when viewed in profile. Aperture slightly invaginated. (Figure 2)
T. complanatum
3.
Smaller species. Mean length 35 µm (main range 30-38 µm; extreme range 1641 µm); mean breadth 15 µm (main range 10-18 µm; extreme range 7-21 µm).
Breadth to length ratio 0.42 to 0.51.
T. lineare
Larger species. Mean length 48 µm (main range 45-52 µm; extreme range 32125 µm); mean breadth 20 µm (main range 16-23 µm; extreme range 1560 µm). Breadth to length ratio 0.41 to 0.43.
T. enchelys
Note: The available biometric data suggests that there is some overlap between
these two species for the size range 32-41µm. For specimens within this size no
clear identification criteria seems to be available.
Ref.
Lengt
M inh (L)
M ax
M
T. penardii
T. com planat um
T. enchel ys
48
40
30
1
50. 2
53
26
-
53. 2
31. 8
-
-
-
50
-
-
-
47
-
46. 6
-
-
48. 4
-
-
16
13
25
23
19
16
15
18
10
14
-
-
-
7
15
8
-
35
29
45
29
34
23
60
20
21
-
-
30
16
30
20
20
15
17
17
19
18
19
M
Trinem a.
Breadth
M in (B)
M ax
34. 8
34. 4
Aver.
-
49
Ogden and Hedley 1980
Gros piet sch 1958
Harni sh 1958
1
2
3
LufCash
tenegger
et al . 1998
4 et al. 1915
5
65
75
24
30
100
125
103
78
52
38
45
40
47
41
32
52
45
26
21
16
43
35
25
1
1
5
1
1
2
3
4
5
3
4
5
Bi omet ri cal data com pil ed f or
1 four
30spec ies
40 of 35
1 24
T. l ineare
41
35
2 18
35
Speci es
Tabl e 1.
-
-
-
-
-
-
-
30. 4
19. 3
29. 9
19. 6
19. 9
16. 9
14. 6
Aver.
-
-
-
-
-
-
-
15
10
18
14
18
-
-
-
-
-
-
-
8
13
30
33
30
20
20
18
16
Depth (D)
M in M ax
-
-
-
-
-
-
-
M
25
13
25
17
20
-
-
-
-
-
-
25. 3
15. 0
23. 7
17. 3
19. 6
-
-
-
-
-
-
8
-
10
-
-
11
-
6
7
7
-
6
-
16
-
17
-
-
20
-
11
20
11
-
8. 5
-
M in M ax M
Aver.
Widt h of aperture
8
15 14.
10(w)
3
5
14 13. 7
10
3
6
13
13
-
-
-
-
-
9
9
-
-
-
13. 1
13. 0
8. 8
9. 2
-
-
-
-
-
-
-
-
5
-
8
-
11
6
7
7
-
6
3
-
-
13
-
16
-
-
20
-
11
20
11
8. 5
6
10
-
10
-
-
-
-
9
9
-
-
-
10. 2
10. 4
8. 8
9. 2
-
-
-
-
-
-
-
-
5
-
-
5
-
-
8
-
10
-
-
-
-
4
3
-
-
-
-
-
-
-
-
-
M
M
M in M ax
Mw.
M ax
in aperture
Dis t. Bet
Aver.
Aver.
and anterior end (a)
9 Height
8
9 8. 8
2
5
10(h)
8. 8 of aperture
8 7. 2
5
8 7. 2
2
4
10
B/ L
8
-
7
-
-
-
-
3
6. 9
-
-
-
-
-
0. 51
0. 40
0. 39
0. 47
0. 42
0. 53
0. 54
7 0.
66
3. 3
-
-
-
M in
Aver.
4 3. 3
0. 50
3 2. 5
0. 33
0. 39
0. 56
0. 48
-
0. 54
0. 60
0. 60
0. 23
0. 44
0. 44
0. 58
0. 38
0. 47
0. 54
0. 49
0. 48
0. 41
M ax
-
-
-
0. 57
0. 62
0. 60
0. 43
0. 41
0. 51
0. 43
M
-
-
-
-
-
-
-
0. 57
0. 61
0. 60
0. 42
0. 41
0. 49
0. 42
Aver.
-
-
-
-
-
-
-
0. 50
0. 42
0. 47
0. 34
0. 42
0. 43
0. 33
M in
D/L
-
-
-
-
-
-
0. 46
0. 69
0. 40
0. 38
0. 38
0. 40
0. 44
M ax
-
-
-
-
-
-
-
0. 47
0. 50
0. 50
0. 36
0. 41
0. 43
0. 40
M
-
-
-
-
-
-
-
0. 48
0. 47
0. 47
0. 37
0. 40
0. 41
0. 40
Aver.
-
-
-
-
-
-
-
1. 00
1. 60
2. 33
4. 00
2. 50
M in
h/ a
-
-
-
-
-
1. 63
1. 60
-
-
-
-
-
2. 75
-
-
-
-
-
2. 00
2. 50
M ax
1. 25
1. 43
3. 00
2. 25
2. 67
M
-
-
-
-
-
-
-
-
-
1. 48
1. 49
2. 79
2. 67
2. 88
Aver.
-
-
-
-
-
-
-
-
-
Figure 1 (left) and 2 (right).
Profile outlines of Trinema penardi (left) and T. complanatum (right)
References
Grospietsch, T. (1958) Wechseltierchen (Rhizopoden) Kosmos Verlag, Stuttgart.
Harnisch, O. (1958). II. Klasse: Wurzelfüssler, Rhizopoda. Die Tierwelt
Mitteleuropas, Band 1: Urtiere-Hohltiere-Würmer, Lieferung 1b (eds P. Brohmer, P.
Ehrmann & G. Ulmer), pp. 1-75, pls. 1-26. Quelle & Meier, Leipzig.
Luftenegger, G., Petz, W., Berger, H., Foissner, W. & Adam, H. (1988) Morphologic
and Biometric Characterization of 24 Soil Testate Amebas (Protozoa, Rhizopoda).
Archiv Fur Protistenkunde, 136, 153-189.
Ogden, C.G. & Hedley, R.H. (1980) An atlas to freshwater testate amoebae Oxford
University Press, Oxford.