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The genus
Tetramitus is an old one being named over 150 years ago! (Perty,
1852). However, it is not at all certain how these very early isolates
are related to those presently now classified as Tetramitus as it
is apparent that morphological criteria alone may not be sufficient.
Tetramitus has been reclassified on the basis of SSUrDNA sequence
analysis (Brown & De Jonckheere, 1999).
This group were previously diagnosed as being limax amoebae of the
family Vahlkampfiiid.
Tetramitus are freshwater although there is a salt tolerant
strain of T. jugosis (fomerly Paratetramitus jugosus)
that exists in a semi-marine locality (Read
et al, 1983). T. jugosis
is common in soils many have been isolated from a variety of locations (Darbyshire
et al, 1976). The possibility of
fully marine Tetramitus members has been discussed (Page,
1983) who reported a personal
communication of a marine Tetramitus salinas by Prof.
Balamuth.
Learamoeba waccamawensis (Sawyer
et al 1998) is 98.7% identical to Tetramitus
rostratus and may therefore be considered to belong to the genus
Tetramitus, but argue that the morphological differences are
sufficient to warrant its inclusion in its own genus (see SSUrDNA vs
Morphology in the Classification of the Amoebae).
Like others in the family Vahlkampiidae, Tetramitus
is primarily bactivorous (Enzein et al,
1989; Read et al,
1983), and some, Didascalus (which is identical to Adelphamoeba
galeacystis, are able to consume bacteria and divide as flagellates
(De Jonckeheere et al, 1997). Tetramitus rostratus
itself was described at first only in its flagellate stage (Perty, 1852
reference in Balamuth et al,
1983) and is able to feed and
divide in this stage.
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| Table 1
The Tetramitus genus renamed
(Brown & De Jonckheere, 1999)
note that most do
not have 4 flagella which is the meaning of Tetramitus.
References
Balamuth, W., Bradbury, P.C. and Schuster, F.L.
(1983). Ultrastructure of the amoeboflagellate Tetramitus
rostratus. J.Protozool. 30(2): 445-455.
Brown, S. and De Jonckheere J. F.
(1999). A reevaluation of the amoeba genus Vahlkampfia
based on SSUrDNA sequences.Eur.J.Protistol. 35:
49-54.
Darbyshire, J. F., Page, F.C., and Goodfellow,
L.P. (1976). Paratetramitus jugosus, an amoebo-flagellate
of soils and freshwater, type-species of Paratetramitus nov.
gen. Protistologica 12: 375-387.
Enzien, M., McKhann, H. I. &
Margulis, L. (1989) Ecology and life history of an amoebomastigote, Paratetramitus
jugosus, from a microbial mat: New evidence for multiple fission. Biol.Bull.
177, 110-129.
Page, F. C. (1983). Marine Gymnamoebae,
Institute of Terrestrial Ecology, NERC.
Read, L. K., Margulis,.L., Stolz, J., Obar, R.,
and Sawyer, T.K. (1983). A new strain of Paratetramitus jugosus
from Laguna Figueroa, Baja California, Mexico. Biol.Bull.
165: 241-264.
Sawyer, T. K., Nerad, T.A, Cahoon, L.B.,
and Nearhoof, J.E.(1998). Learamoeba waccamawensis, N..G.,
N.Sp. (Heterolobosea: Vahkampfiidae), a new temperature-tolerant
cyst-forming soil amoeba. J.Euk.Microbiol. 45(3):
260-264.
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