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]

Stephanosphaera
Stephanosphaera pluvialis
Scientific classification
Kingdom:	Plantae
Division:	Chlorophyta
Class:	Chlorophyceae
Order:	Chlamydomonadales
Family:	Haematococcaceae
Genus:	Stephanosphaera Cohn
Species:	S. pluvialis
Binomial name
Stephanosphaera pluvialis Cohn

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]