Stephanosphaera Explained

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

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.[2] [3]

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.[2] Sexual reproduction is done with gametes, which are isogamous.[2]

Distribution

Stephanosphaera pluvialis is found in freshwater habitats. It tends to occur in rainwater puddles on non-basic rocks, more rarely in lakes.[4] It is rare.

Notes and References

  1. 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 . 10.21900/j.inhs.v5.420 . free .
  2. Book: John D.. Wehr. Robert G.. Sheath. J. Patrick. Kociolek . 2014 . 2 . Freshwater Algae of North America: Ecology and Classification . Nakada. Takashi. Nozaki . Hisayoshi . Chapter 6. Flagellate Green Algae . Elsevier Inc. . 978-0-12-385876-4 .
  3. Book: Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições . 2 . 2006 . Carlos E. M. . Bicudo . Mariângela . Menezes . RiMa Editora . 508 . 857656064X .
  4. A report of Stephanosphaera pluvialis Cohn 1852 (Chlorophyta, Chlamydophyceae) . Kaštovský . Jan . Fottea . 2008 . 8 . 2 . 109–110 . 10.5507/fot.2008.006 . free .