Zooflagellate

Zooflagellates are single-celled eukaryotes with flagella (i.e., flagellates). They are heterotrophic flagellates, as opposed to phytoflagellates, which are photosynthetic. ^[1] The term "zooflagellate" is also used to refer to reproductive cells or zoospores belonging to multicellular organisms, such as fungi. ^[2]

History

Zooflagellates
An illustration of choanoflagellates
Scientific classification (obsolete)
Domain:	Eukaryota
Kingdom:	Protista
Phylum:	Sarcomastigophora
Subphylum:	Mastigophora (flagellates)
Class:	Zoomastigophorea Calkins, 1909

In historical systems of classification during the 20th century, zooflagellates were grouped as a single taxon Zoomastigophora or Zoomastigophorea within the kingdom Protista. ^[3] It included protists that lack chloroplasts and cell walls and have one or more flagella, but not many as in ciliates or opalines, ^{[4] [5]} namely:

• Bicosoecids, composing the order Bicosoecida, distinguished by two unequal flagella. ^[4] They are currently known as a lineage of Stramenopiles, more closely related to algae such as diatoms than to other zooflagellates. ^[6]

• Choanoflagellates, then treated as order Choanoflagellida, distinguished by one anterior flagellum surrounded by a collar. ^{[4] [3]} They are now known as the lineage most closely related to animals. ^[7]

• Various orders of metamonads, ^[8] treated separately at that time: Hypermastigida , Diplomonadida , Oxymonadida , Retortamonadida , Trichomonadida . ^{[4] [3]}

• Kinetoplastids, known as order Kinetoplastida at the time, distinguished by one or two flagella and the presence of the kinetoplast. ^[3] They are closely related to euglenophytes, a group of phytoflagellates. ^[9]

Over time, with the advancements in phylogenetics and ultrastructure studies, the term "zooflagellate" became obsolete as a formal taxon. ^[1] Instead, it was adopted as an informal name to refer to any given group of heterotrophic flagellates, regardless of evolutionary relationships. ^{[10] [11] [12]}

References

1. Taylor, F. J. R. (February 1976). "Flagellate Phylogeny: A Study in Conflicts". The Journal of Protozoology. 23 (1): 28–40. doi:10.1111/j.1550-7408.1976.tb05242.x.
2. Lefèvre E, Bardot C, Noël C, Carrias JF, Viscogliosi E, Amblard C, Sime-Ngando T (5 September 2006). "Unveiling fungal zooflagellates as members of freshwater picoeukaryotes: evidence from a molecular diversity study in a deep meromictic lake". Environmental Microbiology. 9 (1): 61–71. doi:10.1111/j.1462-2920.2006.01111.x. PMID   17227412.
3. Levine ND, Corliss JO, Cox FEG, Deroux G, Grain J, Honigberg BM, Leedale GF, Loeblich AR, Lom J, Lynn D, Merinfeld EG, Page FC, Poljansky G, Sprague V, Vavra J, Wallace FG (1980). "A newly revised classification of the Protozoa". Journal of Protozoology. 27 (1): 37–58. doi: 10.1111/j.1550-7408.1980.tb04228.x . PMID   6989987.
4. Honigberg, B.M.; Balamuth, W.; Bovee, E.C.; Corliss, J.O.; Gojdics, M.; Hall, R.P.; Kudo, R.R.; Levine, N.D.; Loeblich, A.R.; Weiser, J.; Wenrich, D.H. (February 1964). "A Revised Classification of the Phylum Protozoa". The Journal of Protozoology. 11 (1): 7–20. doi:10.1111/j.1550-7408.1964.tb01715.x. PMID   14119564.
5. Cavalier-Smith, T (1995). "Zooflagellate phylogeny and classification". Tsitologiia. 37 (11): 1010–29. PMID   8868448.
6. Jirsová, Dagmar; Wideman, Jeremy G. (2024). "Integrated overview of stramenopile ecology, taxonomy, and heterotrophic origin". The ISME Journal. 18 (1) wrae150. doi: 10.1093/ismejo/wrae150 . PMC   11412368 . PMID   39077993.
7. Steenkamp, Emma T.; Wright, Jane; Baldauf, Sandra L. (January 2006). "The Protistan Origins of Animals and Fungi". Molecular Biology and Evolution. 23 (1): 93–106. doi: 10.1093/molbev/msj011 . PMID   16151185.
8. Cavalier-Smith, Thomas (1 November 2003). "The excavate protozoan phyla Metamonada Grassé emend. (Anaeromonadea, Parabasalia, Carpediemonas, Eopharyngia) and Loukozoa emend. (Jakobea, Malawimonas): their evolutionary affinities and new higher taxa". International Journal of Systematic and Evolutionary Microbiology. 53 (6): 1741–1758. doi: 10.1099/ijs.0.02548-0 . PMID   14657102.
9. Alexei Y. Kostygov; Anna Karnkowska; Jan Votýpka; Daria Tashyreva; Kacper Maciszewski; Vyacheslav Yurchenko; Julius Lukeš (10 March 2021). "Euglenozoa: taxonomy, diversity and ecology, symbioses and viruses". Open Biology . 11: 200407. doi:10.1098/RSOB.200407. ISSN   2046-2441. PMC   8061765 . PMID   33715388. Wikidata   Q125548575.
10. Brugerolle G (1993). "Evolution and Diversity of Amitochondrial Zooflagellates". The Journal of Eukaryotic Microbiology. 40 (5): 616–618. doi:10.1111/j.1550-7408.1993.tb06118.x.
11. Cavalier-Smith T, Chao EE, Thompson CE, Hourihane SL (1996). "Oikomonas, a distinctive zooflagellate related to chrysomonads". Archiv für Protistenkunde. 146 (3–4): 273–279. doi:10.1016/S0003-9365(96)80014-5.
12. Howe AT, Bass D, Vickerman K, Chao EE, Cavalier-Smith T (2009). "Phylogeny, Taxonomy, and Astounding Genetic Diversity of Glissomonadida ord. nov., The Dominant Gliding Zooflagellates in Soil (Protozoa: Cercozoa)". Protist. 160 (2): 159–189. doi:10.1016/j.protis.2008.11.007. ISSN   1434-4610. PMID   19324594.