Stephanosphaera

<i>Stephanosphaera</i>

Stephanosphaera

Genus of algae

Stephanosphaera is a genus of green algae in the family Haematococcaceae, containing the single species Stephanosphaera pluvialis.[1] It forms colonies of flagellated cells. Although it was once placed in the family Volvocaceae,[2] it is not closely related to them; its sister is the unicellular genus Balticola.[3]

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Description

Stephanosphaera pluvialis forms colonies of four or eight cells, arranged in a ring and surrounded by a spherical matrix. Each cell is elongated, irregularly shaped with several protrusions that join the cells together. Cells contain several contractile vacuoles, a rounded stigma, and a single large parietal chloroplast with usually two pyrenoids. Cells have two flagella of equal length.[3][4]

Reproduction

Stephanosphaera pluvialis reproduces both asexually and sexually. Asexual reproduction occurs by autocolony formation: a cell divides until it becomes like a miniature version of the existing colony, and the new colony is released from the cell.[3] Sexual reproduction is done with gametes, which are isogamous.[3]

Distribution

Stephanosphaera pluvialis is found in freshwater habitats. It tends to occur in rainwater puddles on non-basic rocks, more rarely in lakes.[5] It is rare.[1]

References

  1. [1]
    Guiry, M.D.; Guiry, G.M. "Stephanosphaera". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Retrieved 2023-02-15.
  2. [2]
    Kofoid, C.A. (1899). "Plankton studies. III. On Platydorina, a new genus of the family Volvocidae, from the plankton of the Illinois River". Bulletin of the Illinois State Laboratory of Natural History. 5 (9): 419–440, pi. 38. doi:10.21900/j.inhs.v5.420.
  3. [3]
    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 (2 ed.). Elsevier Inc. ISBN 978-0-12-385876-4.
  4. [4]
    Bicudo, Carlos E. M.; Menezes, Mariângela (2006). Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições (2 ed.). RiMa Editora. p. 508. ISBN 857656064X.
  5. [5]
    Kaštovský, Jan (2008). "A report of Stephanosphaera pluvialis Cohn 1852 (Chlorophyta, Chlamydophyceae)". Fottea. 8 (2): 109–110. doi:10.5507/fot.2008.006.
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