Postgaardia
| Postgaardia | |
|---|---|
Scientific classification
| |
| Domain: | Eukaryota |
| Phylum: | Euglenozoa |
| Subphylum: | Postgaardia Cavalier-Smith, 2016[1] |
| Synonyms | |
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Postgaardiais a proposed basalcladeof flagellateEuglenozoa,followingThomas Cavalier-Smith.[2]As of April 2023[update],theInterim Register of Marine and Nonmarine Generatreats the group as a subphylum.[1]A 2021 review of Euglenozoa places Cavalier-Smith's proposed members of Postgaardia in the classSymbiontida.[3]As Euglenozoans may be basaleukaryotes,the Postgaardia may be key to studying the evolution of Eukaryotes, including the incorporation of eukaryotic traits such as the incorporation ofalphaproteobacterialmitochondrialendosymbionts.
Euglenozoa are a large group offlagellateDiscoba.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 clades,i.e.,Kinetoplastea,Diplonemea,Euglenids,andSymbiontida.Euglenozoa are unicellular, mostly around 15–40 μm (0.00059–0.00157 in) in size, although some euglenids get up to 500 μm (0.020 in) long.[4]
Characteristics
[edit]Euglenozoa are characterized by the ultrastructure of theflagella.In addition to the normal supporting microtubules oraxoneme,each contains a rod (calledparaxonemal), which has a tubular structure in one flagellum and a latticed structure in the other. Based on this, two smaller groups are included: thediplonemidsandPostgaardi.[5]
Postgaardea is a third deep-branching euglenozoan clade that may be a sister to Euglenoida but does not branch within them orGlycomonadaon the evolutionary most realistic sequence trees presented in the next three sections, contrary to some poorly resolved earlier trees. They were placed in the new subphylum Postgaardia because they are radically different ultrastructurally from both euglenoids and glycomonads.[2]
Postgaardia arebiciliatefree-living anaerobes covered in epibiotic bacteria in longitudinal rows are the diagnosis. A highly contractile pellicle with multiple evenly spaced microtubules and no morphogenetic pairs that are specifically distinguished. Without cytostomal or reservoir encircling fibers, cemented jaw supports, or hard longitudinal straight cemented rods, thecytopharynxis simplified. Postgaardea is the lone included class in etymology.[2]
Reconstructions of FA ultrastructure in Postgaardi andCalkinsiaconfirmed that they were fundamentally similar and deserved to be classified together as a distinct order Postgaardida and class Postgaardea, as both genera share six finger-like projections.[2]
Taxonomy
[edit]Cavalier-Smith (2017)[6]
- InfraphylumPostgaardiaCavalier-Smith 2016 stat. nov. Cavalier-Smith 2017
- ClassPostgaardeaCavalier-Smith 1998 s.s.[SymbiontidaYubuki et al., 2009]
- OrderBihospitidaCavalier-Smith 2016
- FamilyBihospitidaeCavalier-Smith 2016
- OrderPostgaardidaCavalier-Smith 2003
- FamilyCalkinsiidaeCavalier-Smith 2016
- FamilyPostgaardidaeCavalier-Smith 2016
- OrderBihospitidaCavalier-Smith 2016
- ClassPostgaardeaCavalier-Smith 1998 s.s.[SymbiontidaYubuki et al., 2009]
- InfraphylumPostgaardiaCavalier-Smith 2016 stat. nov. Cavalier-Smith 2017
References
[edit]- ^abPostgaardia.Retrieved through:Interim Register of Marine and Nonmarine Genera.
- ^abcdCavalier-Smith, Thomas (2016)."Higher classification and phylogeny of Euglenozoa".European Journal of Protistology.56:250–276.doi:10.1016/j.ejop.2016.09.003.PMID27889663.
- ^Kostygov, Alexei Y.; Karnkowska, Anna; Tashyreva, Daria; Maciszewski, Kacper & Lukeš, Julius (2021)."Euglenozoa: taxonomy, diversity and ecology, symbioses and viruses".Open Biology.11(3).doi:10.1098/rsob.200407.PMC8061765.PMID33715388.
- ^"Euglenozoa".Encyclopedia of Life.National Museum of Natural History - Smithsonian Institution.Retrieved16 January2020.
- ^Simpson AG (1997). "The Identity and Composition of Euglenozoa".Archiv für Protistenkunde.148(3): 318–328.doi:10.1016/s0003-9365(97)80012-7.
- ^Cavalier-Smith, Thomas (2017)."Euglenoid pellicle morphogenesis and evolution in light of comparative ultrastructure and trypanosomatid biology: Semi-conservative microtubule/Strip duplication, strip shaping and transformation".European Journal of Protistology.61(Pt A): 137–179.doi:10.1016/j.ejop.2017.09.002.PMID29073503.
External links
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