Euglenozoa are a large group of flagellate Discoba. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. Euglenozoa are represented by four major groups, i.e., Kinetoplastea, Diplonemea, Euglenida, and Symbiontida. Euglenozoa are unicellular, mostly around in size, although some euglenids get up to long.
Structure
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
that arise from the flagellar bases; the other two support the dorsal and ventral surfaces of the cell.
Some other euglenozoa feed through absorption, and many euglenids possess , the only eukaryotes outside Diaphoretickes to do so without performing kleptoplasty,
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 and Postgaardi.
Classification
Historically, euglenozoans have been treated as either plants or animals, depending on whether they belong to largely
Photosynthesis groups or not. Hence they have names based on either the International Code of Nomenclature for algae, fungi, and plants (ICNafp) or the International Code of Zoological Nomenclature (ICZN). For example, one family has the name
Euglenaceae under the ICNafp and the name Euglenidae under the ICZN. As another example, the genus name
Dinema is acceptable under the ICZN, but illegitimate under the ICNafp, as it is a later homonym of an orchid genus, so that the synonym
Dinematomonas must be used instead.
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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.
Phylogeny
The phylogeny based on the work of Cavalier-Smith (2016):
A consensus phylogeny following the review by Kostygov et al. (2021):
Taxonomy
Cavalier-Smith (2016/2017)
The following classification of Euglenozoa is as described by Cavalier-Smith in 2016,
Phylum Euglenozoa Cavalier-Smith 1981 emend. Simpson 1997 Euglenobionta
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Subphylum Glycomonada Cavalier-Smith 2016
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Class Diplonemea Cavalier-Smith 1993 emend. Simpson 1997 Diplosonematea;
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Class Kinetoplastea Honigberg 1963 emend. Margulis 1974 Kinetoplastida
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Subclass Prokinetoplastina Vickerman 2004
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Order Prokinetoplastida Vickerman 2004
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Subclass Metakinetoplastina Vickerman 2004
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Order Bodonida* Hollande 1952 em. Vickerman 1976, Kryov et al. 1980
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Order Trypanosomatida Kent 1880 stat. n. Hollande, 1952 emend. Vickerman 2004
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Subphylum Plicomonada Cavalier-Smith 2017
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Infraphylum Postgaardia Cavalier-Smith 2016 stat. nov. Cavalier-Smith 2017
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Infraphylum Euglenoida Bütschli 1884 emend. Senn 1900 stat. nov. Cavalier-Smith, 2017 Euglenophyta;
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Parvphylum Entosiphona Cavalier-Smith 2016 stat. nov. Cavalier-Smith 2017
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Parvphylum Dipilida Cavalier-Smith 2016 stat. nov. Cavalier-Smith 2017
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Superclass Rigimonada* Cavalier-Smith 2016
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Superclass Spirocuta Cavalier-Smith 2016
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Class Peranemea Cavalier-Smith 1993 emend. Cavalier-Smith 2016
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Class Euglenophyceae Schoenichen 1925 emend. Marin & Melkonian 2003 Euglenea (Photosynthetic clade)
Kostygov et al. (2021)
Phylum Euglenozoa Cavalier-Smith 1981 emend. Simpson 1997
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Class Kinetoplastea Honigberg, 1963 emend. Vickerman, 1976
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Subclass Prokinetoplastia Vickerman, 2004
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Order Prokinetoplastida Vickerman, 2004
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Subclass Metakinetoplastia Vickerman, 2004
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Class Diplonemea Cavalier-Smith, 1993
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Class Euglenida Bütschli, 1884 emend. Simpson, 1997
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Clade Olkaspira Lax and Simpson, 2020
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Clade Spirocuta Cavalier-Smith, 2016
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Clade Euglenophyceae Schoenichen, 1925 emend. Marin and Melkonian, 2003
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Order Euglenales Leedale, 1967 emend. Marin and Melkonian, 2003
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Family Euglenaceae Dujardin, 1841 emend. Kim et al., 2010 Euglenidae
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Family Phacaceae Kim, Triemer and Shin 2010 Phacidae
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Order Eutreptiales Leedale, 1967 emend. Marin and Melkonian, 2003
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Order Rapazida Cavalier-Smith, 2016
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Clade Anisonemia Cavalier-Smith, 2016
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Order Anisonemida Cavalier-Smith, 2016
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Clade Aphagea Cavalier-Smith, 1993 emend. Busse and Preisfeld, 2002
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Order Peranemida Cavalier-Smith, 1993
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Clade Alistosa Lax et al., 2020
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Order Petalomonadida Cavalier-Smith, 1993
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Class Symbiontida Yubuki, Edgcomb, Bernhard and Leander, 2009
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