Euglenozoa

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Euglenozoa
Two Euglena.jpg
Two Euglena
Scientific classification
Domain: Eukaryota
(unranked): Excavata
Phylum: Euglenozoa
Cavalier-Smith, 1981[1]
Classes and unplaced genera

Diplonemea
Euglenoidea
Kinetoplastea
Symbiontida
Postgaardi
Calkinsia

Synonyms
  • Euglenoida Cavalier-Smith, 1978

The euglenozoa are a large group of flagellate excavates. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. There are two main subgroups, the euglenids and kinetoplastids. Euglenozoa are unicellular, mostly around 15-40 µm in size, although some euglenids get up to 500 µm long.[2]

Structure[edit]

Most euglenozoa have two flagella, which are inserted parallel to one another in an apical or subapical pocket. In some these are associated with a cytostome or mouth, used to ingest bacteria or other small organisms. This is supported by one of three sets of microtubules that arise from the flagellar bases; the other two support the dorsal and ventral surfaces of the cell.[3]

Some other euglenozoa feed through absorption, and many euglenids possess chloroplasts and so obtain energy through photosynthesis. These chloroplasts are surrounded by three membranes and contain chlorophylls A and B, along with other pigments, so are probably derived from a captured green alga. Reproduction occurs exclusively through cell division. During mitosis, the nuclear membrane remains intact, and the spindle microtubules form inside of it.[3]

The group is characterized by the ultrastructure of the flagella. In addition to the normal supporting microtubules or axoneme, each contains a rod (called paraxonemal), which has a tubular structure in one flagellum and a latticed structure in the other. Based on this, two smaller groups have been included here: the diplonemids and Postgaardi.[4]

Classification[edit]

The euglenozoa are generally accepted as monophyletic. They are related to Percolozoa; the two share mitochondria with disk-shaped cristae, which only occurs in a few other groups.[5] Both probably belong to a larger group of eukaryotes called the excavates.[6] This grouping, though, has been challenged.[7]

Phylogeny[edit]

The phylogeny based on the work of Cavalier-Smith 2016.[8]


Glycomonada
Diplonemea
Diplonemida

Hemistasiidae



Diplonemidae




Kinetoplastea
Prokinetoplastina

Ichthyobodonidae


Metakinetoplastina

Rhynchobodo




Neobodonidae




Parabodonidae




Bodonidae



Trypanosomatidae









Postgaardia
Postgaardea
Bihospitida

Bihospitidae


Postgaardida

Postgaardidae



Calkinsiidae





Euglenoida
Entosiphona
Entosiphonea
Entosiphonida

Entosiphonidae




Dipilida
Stavomonadea
Heterostavia
Heterostavida

Serpenomonadidae



Homostavia
Decastavida

Decastavidae



Keelungiidae



Petalomonadida

Sphenomonadidae



Petalomonadidae






Ploeotarea
Ploeotiida

Lentomonadidae



Ploeotiidae




Spirocuta
Peranemea
Peranemida

Peranemidae




Anisonemia
Anisonemida

Anisonemidae


Natomonadida
Metanemina

Neometanemidae


Rhabdomonadina

Distigmidae



Astasiidae






Acroglissia
Acroglissida

Teloproctidae



Euglenophyceae
Rapazia
Rapazida

Rapazidae



Euglenophycidae
Eutreptiales

Eutreptiaceae


Euglenales

Euglenamorphaceae




Phacaceae



Euglenaceae














Taxonomy[edit]

Phylum Euglenozoa Cavalier-Smith 1981 emend. Simpson 1997[8] [Euglenobionta]

References[edit]

  1. ^ T. Cavalier-Smith (1981). "Eukaryote Kingdoms: Seven or Nine?". BioSystems. 14 (3–4): 461–481. doi:10.1016/0303-2647(81)90050-2. PMID 7337818. 
  2. ^ "Euglenozoa". Retrieved 21 May 2013. 
  3. ^ a b David J. Patterson (1999). "The Diversity of Eukaryotes". American Naturalist. 154 (S4): S96–S124. doi:10.1086/303287. PMID 10527921. 
  4. ^ Alastair G. B. Simpson (1997). "The Identity and Composition of Euglenozoa". Archiv für Protistenkunde. 148: 318–328. doi:10.1016/s0003-9365(97)80012-7. 
  5. ^ Baldauf, S. L.; Roger, A. J.; Wenk-Siefert, I.; Doolittle, W. Ford (2000). "A Kingdom-Level Phylogeny of Eukaryotes Based on Combined Protein Data". Science. 290 (5493): 972–977. doi:10.1126/science.290.5493.972. PMID 11062127. 
  6. ^ Alastair G. Simpson (2003). "Cytoskeletal organization, phylogenetic affinities and systematics in the contentious taxon Excavata (Eukaryota)". International Journal of Systematic and Evolutionary Microbiology. 53 (Pt 6): 1759–1777. doi:10.1099/ijs.0.02578-0. PMID 14657103. 
  7. ^ Cavalier-Smith T (December 2009). "Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree". Biol Lett. 6 (3): 342–5. doi:10.1098/rsbl.2009.0948. PMC 2880060Freely accessible. PMID 20031978. 
  8. ^ a b Thomas Cavalier-Smith (2016). "Higher Classification and Phylogeny of Euglenozoa". European Journal of Protistology. doi:10.1016/j.ejop.2016.09.003. 

External links[edit]