Eudorina


Eudorina is a genus of green algae in the family Volvocaceae, containing about seven species. It has a cosmopolitan distribution in freshwater habitats.

Description

Eudorina colonies typically consist of 16, 32 or 64 cells, each of which is similar to Chlamydomonas reinhardtii. These cells are bedded within an extracellular matrix composed of glycoproteins. Colonies are spherical and motile, with motility derived from the flagellated individual cells. Cells are ovoid or spherical, each with two equal flagella.
There is a single cup-shaped chloroplast with one and a stigma. Multiple contractile vacuoles are scattered throughout the cytoplasm.
Eudorina is facultatively sexual, meaning colonies can reproduce either sexually or asexually. During development, each Chlamydomonas-like cell undergoes several rounds of division to form curved plates called plakeas, which then invert to form daughter colonies before hatching out of the mother colony. Sexual reproduction is anisogamous; cells divide successively and differentiate into sperm packets, or develop into female gametes.

Taxonomy

Although the most common species of Eudorina is very different from the most common species of Pandorina, forms intermediate in morphology between Eudorina and Pandorina exist, such as Pandorina/Eudorina charkowiensis and Pandorina unicocca. These have been reclassified to other genera, namely Colemanosphaera and Yamagishiella, respectively. In particular, Eudorina is very similar to Yamagishiella, differing mainly in its mode of reproduction and number/placement of contractile vacuoles.
Molecular phylogenetic studies show that Eudorina is paraphyletic with respect to Pleodorina and Volvox. Taxonomically, Eudorina has been confused with Pleodorina. In particular, Eudorina illinoisensis blurs the boundaries between the two genera by having four anterior cells which are facultatively somatic. Currently, Eudorina is distinguished from Pleodorina by the absence or presence of obligately somatic cells.
Phylogenetic relationships are as follows (not all species of Eudorina are included: