Pandorina is composed of 8, 16, or sometimes 32 cells, held together at their bases to form a globular or ellipsoidal colony surrounded by mucilage. The cells are ovoid or slightly narrowed at one end to appear keystone- or pear-shaped. Each cell has two flagella with two contractile vacuoles at its base, an eyespot, and a large cup-shaped chloroplast with at least one pyrenoid.[1] The colonies co-ordinate their flagellar movement to create a rolling, swimming motion. Pandorina shows the beginnings of the colony polarity and differentiation seen in Volvox, with anterior cells having larger eyespots.
The taxonomy of Pandorina and Eudorina have been confused because the original description was insufficient to distinguish the two genera.[1] In addition, some species appear to be intermediate in morphology between the two, and have at times been considered part of either genus, such as Pandorina/Eudorina charkowiensis. Currently, these intermediate taxa are placed in two genera, Colemanosphaera and Yamagishiella. Therefore, the genera are separated as follows:[4]
Pandorina: two contractile vacuoles at the base of the flagella; one or multiple pyrenoids; sexual reproduction isogamous;[4] no cellular envelope around each individual cell.[4]
Colemanosphaera: two or three contractile vacuoles at the base of the flagella; multiple pyrenoids in a mature cell; sexual reproduction anisogamous, with fertilization happening outside of the female spheroid; cellular envelope around each individual cell.[5]
Yamagishiella: two contractile vacuoles at the base of the flagella; single basal pyrenoid; sexual reproduction isogamous; cellular envelope around each individual cell.[6]
Eudorina: two apical contractile vacuoles and multiple contractile vacuoles scattered throughout cell; one basal or multiple pyrenoids;[7] sexual reproduction anisogamous;[4] cellular envelope around each individual cell.[6]
↑ Smith, GM. Phytoplankton of Inland Lakes of Wisconsin, Part I, Wisconsin Geological and Natural History Survey, Madison, WI. (1920).
1 2 3 4 Nakada, Takashi; Nozaki, Hisayoshi (2014). "Chapter 6. Flagellate Green Algae". In Wehr, John D.; Sheath, Robert G.; Kociolek, J. Patrick (eds.). Freshwater Algae of North America: Ecology and Classification (2ed.). Elsevier Inc. pp.265–313. ISBN978-0-12-385876-4.
1 2 Nozaki, H.; Kuroiwa, T. (1992). "Ultrastructure of the extracellular matrix and taxonomy of Eudorina, Pleodorina and Yamagishiella gen. nov. (Volvocaceae, Chlorophyta)". Phycologia. 31 (6): 529–541. Bibcode:1992Phyco..31..529N. doi:10.2216/i0031-8884-31-6-529.1.
↑ Yamada, Toshihiro K.; Miyaji, Kazuyuki; Nozaki, Hisayoshi (2008). "A taxonomic study ofEudorina unicocca(Volvocaceae, Chlorophyceae) and related species, based on morphology and molecular phylogeny". European Journal of Phycology. 43 (3): 317–326. Bibcode:2008EJPhy..43..317Y. doi:10.1080/09670260701763484.
↑ Nozaki, H.; Takahara, M.; Nakazawa, A.; Kita, Y.; Yamada, T.; Takano, H.; Kawano, S.; Kato, M. (2002). "Evolution of rbcL group IA introns and intron open reading frames within the colonial Volvocales (Chlorophyceae)". Molecular Phylogenetics and Evolution. 23 (3): 326–38. Bibcode:2002MolPE..23..326N. doi:10.1016/S1055-7903(02)00030-1. PMID12099791.
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