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Pseudophyllomitus
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| Pseudophyllomitus | |
|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Clade: | Sar |
| Clade: | Stramenopiles |
| Phylum: | Bigyra |
| Class: | Eogyrea |
| Order: | Eogyrida Cavalier-Smith 2017[3] |
| Family: | Pseudophyllomitidae Shiratori, Thakur & Ishida 2017[2] |
| Genus: | Pseudophyllomitus Lee 2002[1] |
| Type species | |
| Pseudophyllomitus granulatus (Larsen & Patterson 1990) Lee 2002
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| Species[1] | |
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Pseudophyllomitus is a genus of heterotrophic flagellates with two flagella. It contains four species previously assigned to the genus Phyllomitus, of unknown affinities.[1] It is the only genus of the family Pseudophyllomitidae[2] and order Eogyrida,[3] located in the stramenopile clade MAST-6 along with the genera Mastreximonas and Vomastramonas. This clade and other clades of environmental sequences form the class Eogyrea, the sister group to the labyrinthulomycetes.[4]
Description
[edit]Pseudophyllomitus is a genus of free-living single-celled phagotrophic flagellates with two unequally sized (heterokont) flagella. It is found in freshwater and marine sediments worldwide.[1] Like other members of the Stramenopiles, the anterior flagellum has tubular mastigonemes or hair-like extensions, and the transitional region between the flagellum and the basal body has a helical structure.[2] Cells are flexible and sac-shaped, with the flagella inserted subapically into a pocket. They swim freely, and occasionally glide, with one flagellum directed forward anad the other trailing behind.[1][3] Cells measure 7–21 μm long and 4–5.5 μm wide.[1]
Species of Pseudophyllomitus share morphological similarities to distantly related organisms. For example, their flexibility and the structure of their trichocysts resembles the one observed in the euglenozoans Papus, Rhynchobodo, Hemistasia and Postgaardi.[5] It is also generally similar to the alveolate Palustrimonas, except its flagella insert in separate grooves and its cells are less flexible.[1]
Taxonomy
[edit]The genus Pseudophyllomitus was described in 2002 by protistologist Won Je Lee to accommodate four species previously assigned to Phyllomitus, namely P. apiculatus, P. granulatus, P. salinus, and P. vesiculosus. The type species of Phyllomitus, P. undulans, was originally described by Samuel Friedrich Stein in 1878 as having two flagella that adhere to each other. This characteristic was used to justify the removal of the other species, which lack adherent flagella, into a separate genus.[1]
In 2017, a culture of Pseudophyllomitus vesiculosus was established and molecularly sequenced. A phylogenetic analysis showed that the species belongs to MAST-6, one of the clades of environmental sequences within the Stramenopiles. Several cellular characteristics observed through electron microscopy, particularly regarding the flagellar apparatus, supported its affinity with other Stramenopiles. Based on these findings, the family Pseudophyllomitidae (under the zoological code) or Pseudophyllomitaceae (under the botanical code) was established for the genus.[2] Later in the same year, the order Eogyrida was established for the family, and the class Eogyrea was described to contain all members of the MAST-6 clade (such as Mastreximonas and Vomastramonas) as well as other MAST clades. This class, together with the labyrinthulomycetes (class Labyrinthulea), belongs to the subphylum Sagenista.[3][4]
References
[edit]- ^ a b c d e f g h Lee, Won Je (2002). "Redescription of the Rare Heterotrophic Flagellate (Protista) - Phyllomitus undulans Stein, 1878, and Erection of a New Genus - Pseudophyllomitus gen. n." Acta Protozoologica. 41: 375–381.
- ^ a b c d Shiratori, Takashi; Thakur, Rabindra; Ishida, Ken-ichiro (2017). "Pseudophyllomitus vesiculosus (Larsen and Patterson 1990) Lee, 2002, a Poorly Studied Phagotrophic Biflagellate is the First Characterized Member of Stramenopile Environmental Clade MAST-6". Protist. 168 (4): 439–451. doi:10.1016/j.protis.2017.06.004.
- ^ a b c d Cavalier-Smith, Thomas (5 September 2017). "Kingdom Chromista and its eight phyla: a new synthesis emphasising periplastid protein targeting, cytoskeletal and periplastid evolution, and ancient divergences". Protoplasma. 255 (1): 297–357. doi:10.1007/s00709-017-1147-3. PMC 5756292. PMID 28875267.
- ^ a b Cho, Anna; Tikhonenkov, Denis V.; Lax, Gordon; Prokina, Kristina I.; Keeling, Patrick J. (10 November 2023). "Phylogenomic position of genetically diverse phagotrophic stramenopile flagellates in the sediment-associated MAST-6 lineage and a potentially halotolerant placididean". Molecular Phylogenetics and Evolution. 190 107964. doi:10.1016/j.ympev.2023.107964.
- ^ Tikhonenkov, Denis V.; Gawryluk, Ryan M. R.; Mylnikov, Alexander P.; Keeling, Patrick J. (3 February 2021). "First finding of free-living representatives of Prokinetoplastina and their nuclear and mitochondrial genomes". Scientific Reports. 11 (1) 2946. doi:10.1038/s41598-021-82369-z. ISSN 2045-2322.