The Apusozoa are an
Obazoa phylum comprising several genera of
flagellate eukaryotes. They are usually around 5–20 μm in size, and occur in soils and aquatic habitats, where they feed on
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
. They are grouped together based on the presence of an organic shell or
theca
In biology, a theca (plural thecae) is a sheath or a covering.
Botany
In botany, the theca is related to plant's flower anatomy. The theca of an angiosperm consists of a pair of microsporangia that are adjacent to each other and share a comm ...
under the dorsal surface of the cell.
The name derives from the Ancient Greek words for footless () and animal ().
This phylum is currently defined as containing the
Breviata
''Breviata anathema'' is a single-celled flagellate amoeboid eukaryote, previously studied under the name ''Mastigamoeba invertens''. The cell lacks mitochondria but has remnant mitochondrial genes, and possesses an organelle believed to be a modif ...
and the
Apusomonadida. However, it currently usually is viewed as paraphyletic, with the Breviata as more basal. The opisthokonts appear to have emerged as sister of the apusomonadida. It has been suggested that the
Mantamonadida be classified in Apusozoa.
The
ancyromonadida
Ancyromonadida or Planomonadida is a small group of biflagellated protists found in the soil and in aquatic habitats, where they feed on bacteria.Cavalier-Smith, T. (2013)Early evolution of eukaryote feeding modes, cell structural diversity, and ...
appear to be
Varisulca
Varisulca was a proposed basal Podiate taxon. It encompassed several lineages of heterotrophic protists, most notably the ancyromonads (planomonads), collodictyonids (diphylleids), rigifilids (''Rigifila'', ''Micronuclearia'') and mantamonadi ...
, Planomonadida, shifting them possibly more basal than the Amoebozoa, or less basal. While some classification systems have placed
Hemimastigida in Apusozoa, 2018 research indicated that
hemimastigotes (/
Hemimastix/
Spironemidae) are their own
supra-kingdom.
Characteristics
The apusomonads have two flagella inserted at right angles, near the anterior of the cell. They move by gliding, with one flagellum trailing along the side and one directed to the anterior.
The form of the
mitochondria varies between the different orders. Among the apusomonads they have tubular
cristae, the ancyromonads flat cristae, and the hemimastigids ambiguous or sacculate cristae. This characteristic was originally considered a good indicator of relationships, but is now known to vary even among close relatives.
References
External links
Amorphea phyla
Taxa named by Thomas Cavalier-Smith
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