Biology:Stephanosphaera
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] The name comes from the Greek roots stephanos, meaning "crown", and sphaira, meaning "ball".[4]
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][5]
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.[6] It is rare.[1]
References
- ↑ 1.0 1.1 Guiry, M.D.; Guiry, G.M. (2008). "Stephanosphaera". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org/browse/taxonomy/?id=44243.
- ↑ 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.
- ↑ 3.0 3.1 3.2 3.3 Nakada, Takashi; Nozaki, Hisayoshi (2014). "Chapter 6. Flagellate Green Algae". Freshwater Algae of North America: Ecology and Classification (2 ed.). Elsevier Inc.. ISBN 978-0-12-385876-4.
- ↑ Shayler, Hannah; Siver, Peter A. (2004). "Stephanosphaera". Carolina Lucid Key to Freshwater Algae. Connecticut College. https://fmp.conncoll.edu/Silicasecchidisk/LucidKeys3.5/Keys_v3.5/Carolina35_Key/Media/Html/Stephanosphaera_Main.html.
- ↑ Bicudo, Carlos E. M.; Menezes, Mariângela (2006). Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições (2 ed.). RiMa Editora. pp. 508. ISBN 857656064X.
- ↑ 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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