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This genera is in some state of confusion!  It has been assumed that Mastigamoeba and  Phreatamoeba are synonymous but this has been challenged (Milyutina et al, 2001).  Mastigamoeba balamuthi (old name Phreatamoeba balamuthi) was isolated from a well in Gambia, West Africa (Chávez et al, 1986).  It is unusual in having only one flagella in that stage, but the ability to transform into a flagellate suggests a kinship with Vahlkampfiidae, however, SSUrDNA analysis places Mastigamoeba balamuthi   far from the Vahlkampfiidae and its nearest relative (of those analysed) seems to be Dictyostelium (Sogin et al, 1996; Hinkle et al, 1994). However a more recent detailed morphological analysis  (Walker et al, 2001) concludes that Mastigamoeba together with other amoeboid genera Mastigella, Mastigina and Peloxyma represent a group "the pelobionts" which is a sister group to Eumycetozoa (which includes amoeboid "Physarum" and "Hyperamoeba" ).  Another analysis (Milyutina et al, 2001) suggests that this is not the case.  Instead Mastigamoeba is differentiated from Phreatamoeba, and Pelomyxa is included with Entamoeba and Endamoeba in the Archamoebae (Milyutina et al, 2001). The flagellate stage does not reproduce and  is without a cyclostome, rostrum or collar. Mastigamoeba balamuthi is multinucleate with a length of between 11 and 160mm, in addition to having a flagellate phase it also produces cysts 9-18mm in diameter without pores.  The nuclear divisions are synchronous and then flagella has a cone-like microtubular complex associated with the nucleus similar to that found in Physarum polycephalum (a true slime mould) (Wright et al, 1979).  Taken together is seems that Mastigamoeba may be related to the slime moulds (Wright et al, 1979).  The situation has more recently been the subject of a very detailed molecular study (Baptiste et al, 2002) in which 100 genes from Dictyostelium, Entamoeba and Mastigamoeba balamuthi ATCC 30984 were compared.  The conclusion of this study was to support the existence of the subphylum "Conosa" erected earlier by Cavalier-Smith (Cavalier-Smith, 1998), to include the three genera (amongst others).  Entamoeba however, is strongly suspected of harbouring a large number of genes from bacteria! (). This would greatly complicate matters if for example Mastigamoeba also has significant numbers of bacterial genes.  It is already clear that Mastigamoeba contains an inorganic pyrophosphate-dependent phosphofructosokinase that is more closely related to eubacterial genes that fellow eukaryotes (Muller et al, 2001). 

The status of the mitochondria in Mastigamoeba too is confusing, although some place the group in the order Pelobiontida ( a group lacking mitochondria) (Stiller et al, 1998), the original description of Phreatamoeba balamuthi, clearly stated that this amoeba "contains cytoplasmic organelles (Fig.11) ultra-structurally similar to the type of mitochondria characteristic of organisms living in low-oxygen environments".  A complication is that Stiller and coworkers (Stiller et al, 1998) studied  Mastigamoeba invertens, and the it seems likely that it and M. balamuthi are not closely related (Milyutina et al, 2001).  A further complication is that a pathogenic amoebic genera called Balamuthia exists! (see Balamuthia)

A thorough analysis (Walker et al, 2001) of the ultra-structure of the flagella, basal body and mitochondria in M. punctachora, M. simplex, and Mastigella commutans suggested a relationship between Mastigamoeba and the pelobionts. Mastigamoeba may be related to Mastigina and/or Mastigella.


Mastigamoeba at the Protist Information Server
Described species:-
M. aspera (150-200 mm in length), two contractile vacuoles.
M. balamuthi (11-160 mm in length), 
M. hylae (80-135mm in length), From the hind gut of amphibia. Flagellum about 10mm long.
M. invertens
M. longfilum (30mm in length), Contractile vacuole at front. Flagellum about 60mm long.
M. punctachora (), Isolated from a freshwater pond in Sidney, Australia (Bernard et al, 2000)
M. schizophrenia (), (Simpson et al, 1997)
M. setosa (c140mm in length) (Goldschmidt, 1907)
M. simplex (), (Bernard et al, 2000)
Strains available:-
Phreatamoeba balamuthi. CCAP 1557/1 ATCC 30984
Mastigamoeba invertens ATCC 50338 'Bermuda' and 50409 AP-1
Mastigamoeba aspera
Mastigamoeba sp ATCC 50617


Bapteste, E., Brinkmann, H., Lee, J. A., Moore, D. V., Sensen, C. W., Gordon, P., Durufle, L., Gaasterland, T., Lopez, P., Muller, M. & Philippe, H. (2002) The analysis of 100 genes supports the grouping of three highly devergent amoebae: Dictyostelium, Entamoeba, and Mastigamoeba. PNAS. 99, 1414-1419.

Bernard, C., Simpson, A. G. B. & Patterson, D. J. (2000) Some free-living flagellates (Protista) from anoxic habitats. Ophelia. 52, 113-142.

Chávez, L. A., Balamuth, W., & Gong, T. (1986). "A light and electron microscopic study of a new polymorphic free-living amoeba. Phreatamoeba balamuthi n.g, n.sp." J.Protozool. 33(3): 397-404.

Goldschmidt, R. (1907). "Uber die lebensgeschichte der Mastigella vitrea n.sp. und Mastigina setosa n sp. Arch.Protistenkd.Suppl. 1, 83-168.

Hinkle, G., Leipe, D.D., Nerad, T.A. & Sogin, M.L. (1994). "The unusually long small subunit ribosomal RNA of Phreatamoeba balamuthi." Nuc.Acids Res. 22: 465-469.

Kudo, R.R. (1966). "Protozoology." 5th Edition, Charles C Thomas Publisher.

Milyutina, I. A., Aleshin, V. V., Mikrjukov, K. A., Kedrova, O. S. & Petrov, N. B. (2001) The unusually long small subunit ribosomal RNA gene found in amitochondriate amoeboflagellate Pelomyxa palustris: its rRNA predicted secondary structure and phylogenetic implication., Gene. 272, 131-139.

Simpson, A. G. B., Bernard, C., Fenchel, T. & Patterson, D. J. (1997) The organisation of Mastigamoeba schizophrenia n. sp.: more evidence of ultrastructural idiosyncrasy and simplicity in pelobiont protists., Eur. J. Protistol. 33, 87-98.

Sogin, M. L., Silberman, J.D, Hinkle, G. & Morrison, H.G. (1996). "Problems with molecular diversity in the eukarya.".Society of General Microbiology Symposium: Evolution of microbial Life ed.Roberts, D.M., Sharp, P., Alderson, G. & Collins, M.A. Cambridge University Press. pp167-184.

Walker, G., Simpson, A. G. B., Edgcomb, V., Sogin, M. L. & Patterson, D. J. (2001) "Ultrastructural identies of Mastigamoeba punctachora, Mastigamoeba simplex and Mastigella commutans and assessment of hypotheses of relatedness of the pelobionts (Protista)"., Eur.J.Protistol. 37, 25-49.

Wright, M., Moisand, A., & Mir, L. (1979). "The structure of the flagellar apparatus of the swarm cells of Physarum polycephalum." Protoplasma 100: 231-250.

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