Euglenophyceae

Euglenophyceae
Euglena viridis , by Ehrenberg
Scientific classification
Domain:	Eukaryota
Clade:	Discoba
Phylum:	Euglenozoa
Class:	Euglenida
Clade:	Spirocuta
Clade:	Euglenophyceae Schoenichen, 1925 emend. Marin & Melkonian, 2003 [1] [2]
Type genus
Euglena Ehrenberg, 1830 [1]
Orders
Rapazida Eutreptiales Euglenales
Synonyms
Euglenea Butschli, 1884 emend. Busse & Preisfeld, 2002 [2]

Euglenophyceae (ICNafp, proposed as a class) or Euglenea (ICZN, proposed as a class) is an unranked clade of single-celled algae belonging to the phylum Euglenozoa. ^{[2] [3]} They have chloroplasts originated from an event of secondary endosymbiosis with a green alga. They are distinguished from other algae by the presence of paramylon as a storage product and three membranes surrounding each chloroplast. ^[4]

Description

Euglenophyceae are unicellular algae, protists that contain chloroplasts. Their chloroplasts originated from a secondary endosymbiosis with a green alga, particularly from the order Pyramimonadales, ^[5] and contain chlorophylls a and b. ^[2] Some have secondarily lost this ability and evolved toward osmotrophy. In addition to photosynthetic plastids, most species have a photosensitive eyespot. ^[3]

Ecology

Euglenophyceae are mainly present in the water column of freshwater habitats. They are abundant in small eutrophic water bodies of temperate climates, where they are capable of forming blooms, including toxic blooms such as those caused by Euglena sanguinea . In tropical climate, blooms are common in ponds. In marine environments they have been reported in a lower amount. Some species are capable of migrating vertically through the sand along with the cycles of ocean tides. Two lineages of Euglenophyceae are part of the marine plankton: Rapazida and Eutreptiales. Eutreptiales can amount up to 46% of the total phytoplankton biomass when blooming in eutrophic coastal waters. ^[3]

Classification

Euglenophyceae encompasses three taxonomic groups: the mixotrophic Rapaza viridis and two mainly phototrophic orders, Euglenales and Eutreptiales. ^{[1] [3] [6]} The classification is as follows (species numbers based on AlgaeBase): ^[7]

• Order Euglenales Leedale, 1967 emend. Marin & Melkonian, 2003
  • Family Euglenaceae [Euglenidae] Dujardin, 1841 emend. Kim et al., 2010
    • Colacium Ehrenberg, 1834 – 17 spp.
    • Cryptoglena Ehrenberg, 1831 – 11 spp.
    • Euglena Ehrenberg, 1830 – 174 spp.
    • Euglenaformis Bennett & Triemer, 2014 – 3 spp.
    • Euglenaria Karnkowska, Linton & Kwiatowski, 2010 – 4 spp.
    • Monomorphina Mereschkowsky, 1877 – 17 spp.
    • Strombomonas Deflandre, 1930 – 99 spp.
    • Trachelomonas Ehrenberg, 1834 – 410 spp.
  • Family Phacaceae [Phacidae] Kim, Triemer & Shin, 2010
    • Discoplastis Triemer, 2006 – 6 spp.
    • Flexiglena Zakryś & Łukomska, 2020 – 1 sp.
    • Lepocinclis Perty, 1849 – 90 spp.
    • Phacus Dujardin, 1841 – 188 spp.
• Order Eutreptiales
  • Family Eutreptiaceae [Eutreptiidae] Hollande, 1942
    • Eutreptia Perty, 1852 – 11 spp.
    • Eutreptiella da Cunha, 1914 – 9 spp.
• Order Rapazida Cavalier-Smith, 2016
  • Family Rapazidae Cavalier-Smith, 2016
    • Rapaza Yamaguchi, Yubuki & Leander, 2012 – 1 sp.

Several genera assigned to Euglenophyceae are considered incertae sedis , because the lack of genetic data makes their phylogenetic position unresolved: ^[3]

• Ascoglena Stein, 1878 – 4 spp.
• Euglenamorpha Wenrich, 1924 – 2 spp.
• Euglenopsis Klebs, 1892 – 11 spp.
• Glenoclosterium Carter, 1869 – 1 sp.
• Hegneria Brumpt & Lavier, 1924 – 1 sp.
• Klebsina Silva, 1961 – 1 sp.
• Euglenocapsa Steinecke, 1932 – 1 sp.
• Menoidium Perty, 1852 – 28 spp.
• Parmidium Christen, 1962 – 10 spp.

References

1. Birger Marin; Anne Palm; Max Klingberg; Michael Melkonian (1 April 2003). "Phylogeny and taxonomic revision of plastid-containing euglenophytes based on SSU rDNA sequence comparisons and synapomorphic signatures in the SSU rRNA secondary structure". Protist . 154 (1): 99–145. doi:10.1078/143446103764928521. ISSN   1434-4610. PMID   12812373. Wikidata   Q34206703.
2. Sina M. Adl; David Bass; Christopher E. Lane; et al. (1 January 2019). "Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes". Journal of Eukaryotic Microbiology . 66 (1): 4–119. doi:10.1111/JEU.12691. ISSN   1066-5234. PMC   6492006 . PMID   30257078. Wikidata   Q57086550.
3. 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.
4. Lee RE (2018). Phycology (5th ed.). Cambridge University Press. doi:10.1017/9781316407219. ISBN   978-1-107-55565-5.
5. Gordon Lax; Alastair G. B. Simpson (16 August 2020). "The Molecular Diversity of Phagotrophic Euglenids Examined Using Single-cell Methods". Protist . 171 (5): 125757. doi:10.1016/J.PROTIS.2020.125757. ISSN   1434-4610. PMID   33126020. Wikidata   Q101127864.
6. Carlos E. de M. Bicudo; Mariângela Menezes (16 March 2016). "Phylogeny and Classification of Euglenophyceae: A Brief Review". Frontiers in Ecology and Evolution. 4. doi: 10.3389/FEVO.2016.00017 . ISSN   2296-701X. Wikidata   Q57898656.
7. Guiry MD, Guiry GM (25 May 2020). "AlgaeBase". World-wide electronic publication, National University of Ireland, Galway. Retrieved 30 April 2024.