The Percolozoa are a group of colourless, non-photosynthetic
Excavata
Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free- ...
, including many that can transform between
amoeboid
An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopo ...
,
flagellate, and
cyst
A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...
stages.
Characteristics
Most Percolozoa are found as bacterivores in soil, fresh water and occasionally in the ocean. The only member of this group that is infectious to humans is ''
Naegleria fowleri
''Naegleria fowleri'', colloquially known as a "brain-eating amoeba", is a species of the genus ''Naegleria'', belonging to the phylum Percolozoa, which is technically not classified as true amoeba, but a shapeshifting amoeboflagellate excava ...
'', the causative agent of the often fatal disease
amoebic meningitis. The group is closely related to the
Euglenozoa, and share with them the unusual characteristic of having
mitochondria with discoid
cristae. The presence of a ventral feeding groove in the flagellate stage, as well as other features, suggests that they are part of the
Excavata
Excavata is a major supergroup of unicellular organisms belonging to the domain Eukaryota. It was first suggested by Simpson and Patterson in 1999 and introduced by Thomas Cavalier-Smith in 2002 as a formal taxon. It contains a variety of free- ...
group.
The amoeboid stage is roughly cylindrical, typically around
20-40 μm in length. They are traditionally considered lobose amoebae, but are not related to the others, and unlike them, do not form true lobose
pseudopods
A pseudopod or pseudopodium (plural: pseudopods or pseudopodia) is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement. Filled with cytoplasm, pseudopodia primarily consist of actin filamen ...
. Instead, they advance by eruptive waves, where hemispherical bulges appear from the front margin of the cell, which is clear. The flagellate stage is slightly smaller, with two or four anterior flagella anterior to the feeding groove.
Usually, the amoeboid form is taken when food is plentiful, and the flagellate form is used for rapid locomotion. However, not all members are able to assume both forms. The genera ''
Percolomonas
''Percolomonas'' is a genus of free-living flagellate Heteroloboseans, forming a clade with ''Stephanopogon''.
The genus includes six described species (see infobox). However, ''P. cosmopolitus'' is likely a species complex containing multiple c ...
'', ''
Lyromonas
Lyromonas is a genus of Excavata unicellular organism
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms f ...
'', and ''
Psalteriomonas
''Psalteriomonas'' is a genus of excavates in the group of Heterolobosea
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.
Characteristics
Mos ...
'' are known only as flagellates, while ''
Vahlkampfia
''Vahlkampfia'' is a genus of amoeboids in Heterolobosea
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.
Characteristics
Most Percolozoa ar ...
'', ''
Pseudovahlkampfia
''Pseudovahlkampfia'' is a genus of Excavates
It includes the species ''Pseudovahlkampfia emersoni''.
References
Percolozoa
Excavata genera
{{Excavata-stub ...
'', and most
acrasid
The family Acrasidae (International Code of Zoological Nomenclature, ICZN, or Acrasiomycota, ICBN) is a family of slime molds which belongs to the Excavata, excavate group Percolozoa. The name element - comes from the Greek ''akrasia'', meaning ...
s do not have flagellate stages. As mentioned above, under unfavourable conditions, the acrasids aggregate to form sporangia. These are superficially similar to the sporangia of the
dictyostelid
The dictyostelids (Dictyostelia/Dictyostelea, ICZN, or Dictyosteliomycetes, ICBN) are a group of cellular slime molds, or social amoebae.
Multicellular behavior
When food (normally bacteria) is readily available dictyostelids behave as individu ...
s, but the amoebae only aggregate as individuals or in small groups and do not die to form the stalk.
Terminology and classification
These are collectively referred to as schizopyrenids, amoeboflagellates, or vahlkampfids. They also include the acrasids, a group of social amoebae that aggregate to form
sporangia
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cyc ...
. The entire group is usually called the Heterolobosea, but this may be restricted to members with amoeboid stages.
One Heterolobosea classification system is:
* Order
Schizopyrenida
Schizopyrenida is an order of Heterolobosea.
It contains ''Naegleria fowleri
''Naegleria fowleri'', colloquially known as a "brain-eating amoeba", is a species of the genus ''Naegleria'', belonging to the phylum Percolozoa, which is techn ...
** Family
Vahlkampfiidae
Vahlkampfiidae is a family of Heterolobosea.
It includes the following genera:
* '' Monopylocystis''
* ''Naegleria''
* '' Neovahlkampfia''
* '' Paravahlkampfia''
* ''Psalteriomonas''
* '' Sawyeria''
* '' Tetramitus''
* '' Vahlkampfia''
* '' Will ...
** Family
Gruberellidae
Gruberellidae is a family of Heterolobosea
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.
Characteristics
Most Percolozoa are found as bact ...
* Order
Acrasida
The family Acrasidae ( ICZN, or Acrasiomycota, ICBN) is a family of slime molds which belongs to the excavate group Percolozoa. The name element - comes from the Greek ''akrasia'', meaning "acting against one's judgement". This group consists ...
** Family
Acrasidae
The family Acrasidae ( ICZN, or Acrasiomycota, ICBN) is a family of slime molds which belongs to the excavate group Percolozoa. The name element - comes from the Greek ''akrasia'', meaning "acting against one's judgement". This group consists ...
''Pleurostomum flabellatum'' has recently been added to Heterolobosea.
Phylogeny
Based on the cladogram from Tolweb and updated with new data from Pánek & Čepička 2012 and Pánek, Ptackova & Čepička 2014.
Taxonomy
Phylum Percolozoa
Cavalier-Smith 1991
* Subphylum
Pharyngomonada
** Class
Pharyngomonadea acropharyngomonadidea*** Order
Pharyngomonadida acropharyngomonadida**** Family
Pharyngomonadidae Cavalier-Smith 2008 Cavalier-Smith 2008">acropharyngomonadidae Cavalier-Smith 2008***** Genus ''
Pharyngomonas''
Cavalier-Smith 2008 'Macropharyngomonas''_nomen_nudum.html" ;"title="Macropharyngomonas.html" ;"title="'Macropharyngomonas">'Macropharyngomonas'' nomen nudum">Macropharyngomonas.html" ;"title="'Macropharyngomonas">'Macropharyngomonas'' nomen nudum* Subphylum Tetramitia
Cavalier-Smith 1993 emend. Cavalier-Smith 2008
** Genus ?''Costiopsis''
Senn 1900
** Genus ?''Hoehnmastix''
Skvortzov 1974
** Genus ?''Planiosculum''
Szabados 1948
** Genus ?''
Protomyxomyces''
Cunningham 1881
** Genus ?''
Protonaegleria''
Michel & Raether 1985
** Genus ?''
Pseudovahlkampfia
''Pseudovahlkampfia'' is a genus of Excavates
It includes the species ''Pseudovahlkampfia emersoni''.
References
Percolozoa
Excavata genera
{{Excavata-stub ...
''
Sawyer 1980
** Genus ?''
Schizamoeba''
Davis 1926
** Genus ?''
Tetramastigamoeba''
Singh & Hanumaiah 1977
** Genus ?''
Trimastigamoeba''
Whitmore 1911
** Genus ?''
Wasielewskia''
Hartmann & Schuessler 1913
** Order ?
Euhyperamoebida
*** Family
Euhyperamoebidae Goodkov & Seravin 1984 Goodkov, Seravin & Railkin 1982">yperamoebidae Goodkov, Seravin & Railkin 1982**** Genus ''
Euhyperamoeba''
Goodkov & Seravin 1984 'Hyperamoeba''_
Goodkov,_Seravin_&_Railkin_1982_non_Alexeieff_1923.html" ;"title="Hyperamoeba.html" ;"title="'Hyperamoeba">'Hyperamoeba''
Goodkov, Seravin & Railkin 1982 non Alexeieff 1923">Hyperamoeba.html" ;"title="'Hyperamoeba">'Hyperamoeba''
Goodkov, Seravin & Railkin 1982 non Alexeieff 1923** Order Selenaionida
Hanousková, Táborský & Čepička 2018
*** Family Selenaionidae
Hanousková, Táborský & Čepička 2018
**** Genus ''Selenaion koniopes''
Park, De Jonckheere & Simpson 2012
**** Genus ''
Dactylomonas''
Hanousková, Táborský & Čepička 2018
** Order
Neovahlkampfiida
*** Family
Neovahlkampfiidae
**** Genus ''
Neovahlkampfia''
Brown & de Jonckheere 1999
** Class
Lyromonadea Cavalier-Smith 1993
*** Order
Paravahlkampfiida
**** Family
Paravahlkampfiidae
***** Genus ''
Fumarolamoeba''
De Jonckheere, Murase & Opperdoes 2011
***** Genus ''
Paravahlkampfia''
Brown & de Jonckheere 1999
*** Order
Lyromonadida Cavalier-Smith 1993
**** Family
Lyromonadidae
Lyromonas is a genus of Excavata unicellular organism
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms f ...
Cavalier-Smith 1993
***** Genus ''
Lyromonas
Lyromonas is a genus of Excavata unicellular organism
A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms f ...
''
Cavalier-Smith 1993
**** Family
Plaesiobystridae
***** Genus ''
Pernina''
El Kadiri, Joyon & Pussard 1992
***** Genus ''
Euplaesiobystra''
Park et al. 2009
***** Genus ''
Plaesiobystra''
***** Genus ''
Heteramoeba''
Droop 1962
**** Family
Gruberellidae
Gruberellidae is a family of Heterolobosea
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.
Characteristics
Most Percolozoa are found as bact ...
Page & Blanton 1985
***** Genus ''
Gruberella''
Page 1984 non Gruber 1889 non Corliss 1960
***** Genus ''
Vrihiamoeba''
Murase, Kawasak & Jonckheere 2010
***** Genus ''
Oramoeba''
***** Genus ''
Stachyamoeba''
Page 1975
**** Family
Psalteriomonadidae Cavalier-Smith 1993
***** Genus ''
Pseudoharpagon''
Panek et al. 2012
***** Genus ''
Sawyeria''
O'Kelly et al. 2003
***** Genus ''
Psalteriomonas
''Psalteriomonas'' is a genus of excavates in the group of Heterolobosea
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.
Characteristics
Mos ...
''
Broers et al. 1990
***** Genus ''
Pseudomastigamoeba''
***** Genus ''
Harpagon''
Panek et al. 2012
***** Genus ''
Monopylocystis''
O'Kelly et al. 2003
** Class
Heterolobosidea
*** Order
Acrasida
The family Acrasidae ( ICZN, or Acrasiomycota, ICBN) is a family of slime molds which belongs to the excavate group Percolozoa. The name element - comes from the Greek ''akrasia'', meaning "acting against one's judgement". This group consists ...
Schröter 1886
**** ?Genus ''
Allovahlkampfia''
Walochnik & Mulec 2009
**** ?Genus ''
Solumitrus''
Wang et al. 2011
**** Family
Acrasidae
The family Acrasidae ( ICZN, or Acrasiomycota, ICBN) is a family of slime molds which belongs to the excavate group Percolozoa. The name element - comes from the Greek ''akrasia'', meaning "acting against one's judgement". This group consists ...
Poche 1913
***** Genus ''
Acrasis
The family Acrasidae (ICZN, or Acrasiomycota, ICBN) is a family of slime molds which belongs to the excavate group Percolozoa. The name element - comes from the Greek ''akrasia'', meaning "acting against one's judgement". This group consists ...
''
van Tieghem 1880
***** Genus ''
Pocheina''
Loeblich & Tappan 1961
**** Family ?
Guttulinopsidae Olive 1970 Berl. 1888; Guttulinopsaceae">uttulinidae Berl. 1888; Guttulinopsaceae***** Genus ''
Guttulina''
Cienkowski 1873 non D’Orbigny 1839
***** Genus ''
Guttulinopsis''
Olive 1901
***** Genus ''
Rosculus''
Hawes 1963
*** Order
Schizopyrenida
Schizopyrenida is an order of Heterolobosea.
It contains ''Naegleria fowleri
''Naegleria fowleri'', colloquially known as a "brain-eating amoeba", is a species of the genus ''Naegleria'', belonging to the phylum Percolozoa, which is techn ...
Singh 1952 s.s.
**** Family
Naegleriidae Kirby et al. 2015">ulamoebidae Kirby et al. 2015***** Genus ''
Aurem''
Jhin & Park 2018
***** Genus ''
Pleurostomum''
Namyslowski 1913
***** Genus ''
Tulamoeba''
Park et al. 2009
***** Genus ''
Marinamoeba''
De Jonckheere et al. 2009
***** Genus ''
Willaertia''
de Jonckheere et al. 1984
***** Genus ''
Naegleria
''Naegleria'' is a free living amoebae protist genus consisting of 47 described species often found in warm aquatic environments as well as soil habitats worldwide. It has three life cycle forms: the amoeboid stage, the cyst stage, and the flage ...
''
Aléxéieff 1912 Trimastigamoeba''_
Whitmore_1911;_''Didascalus.html" ;"title="'
Trimastigamoeba''
Whitmore 1911; ''Didascalus">'
Trimastigamoeba''
Whitmore 1911; ''Didascalus''
Singh 1952]
**** Family
Vahlkampfiidae
Vahlkampfiidae is a family of Heterolobosea.
It includes the following genera:
* '' Monopylocystis''
* ''Naegleria''
* '' Neovahlkampfia''
* '' Paravahlkampfia''
* ''Psalteriomonas''
* '' Sawyeria''
* '' Tetramitus''
* '' Vahlkampfia''
* '' Will ...
Jollos 1917 s.s. etramitaceae***** Genus ''
Tetramitus''
Perty 1852 'Copromastix''_
Aragao_1916;_''Adelphamoeba.html" ;"title="Copromastix.html" ;"title="'Copromastix">'Copromastix''
Aragao 1916; ''Adelphamoeba">Copromastix.html" ;"title="'Copromastix">'Copromastix''
Aragao 1916; ''Adelphamoeba''
Napolitano, Wall & Ganz 1970, ''Learamoeba''
Sawyer et al. 1998, ''Paratetramitus''
Darbyshire, Page & Goodfellow 1976, ''Singhamoeba''
Sawyer, Nerad & Munson 1992; ''Schizopyrenus''
Singh 1952]
***** Genus ''
Vahlkampfia
''Vahlkampfia'' is a genus of amoeboids in Heterolobosea
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.
Characteristics
Most Percolozoa ar ...
''
Chatton & LaLung-Bonnaire 1912
**** Family
Percolomonadidae Cavalier-Smith 1993 hoanogasteraceae***** Genus ''
Percolomonas
''Percolomonas'' is a genus of free-living flagellate Heteroloboseans, forming a clade with ''Stephanopogon''.
The genus includes six described species (see infobox). However, ''P. cosmopolitus'' is likely a species complex containing multiple c ...
''
Fenchel & Patterson 1986 'Choanogaster''_
Pochmann_1959.html" ;"title="Choanogaster.html" ;"title="'
'Choanogaster''_
Pochmann_1959">Choanogaster.html"_;"title="'Choanogaster">'Choanogaster''_
Pochmann_1959****_Family_Stephanopogonidae.html" ;"title="Choanogaster">'Choanogaster''
Pochmann 1959">Choanogaster.html" ;"title="'Choanogaster">'Choanogaster''
Pochmann 1959**** Family Stephanopogonidae">Choanogaster">'Choanogaster''
Pochmann 1959">Choanogaster.html" ;"title="'Choanogaster">'Choanogaster''
Pochmann 1959**** Family Stephanopogonidae
Corliss 1961
***** Genus ''
Stephanopogon''
Entz 1884
History
The Heterolobosea were first defined by F. C. Page, Page and R. L. Blanton, Blanton in 1985 as a class of amoebae, and so only included those forms with amoeboid stages.
Cavalier-Smith
Thomas (Tom) Cavalier-Smith, FRS, FRSC, NERC Professorial Fellow (21 October 1942 – 19 March 2021), was a professor of evolutionary biology in the Department of Zoology, at the University of Oxford.
His research has led to disc ...
created the phylum Percolozoa for the extended group, together with the enigmatic flagellate ''
Stephanopogon''.
[
]
Cavalier-Smith maintained the Heterolobosea as a class for amoeboid forms. He has defined Percolozoa as "Heterolobosea plus
Percolatea
Percolatea are a class of excavates in the phylum Percolozoa.
See also
* Percolozoa
The Percolozoa are a group of colourless, non-photosynthetic Excavata, including many that can transform between amoeboid, flagellate, and cyst stages.
Cha ...
classis nov."
References
External links
Tree of Life Heterolobosea
{{Taxonbar, from=Q22094454
Bikont phyla
Taxa named by Thomas Cavalier-Smith