The Chlorophyceae are one of the classes of green algae, distinguished mainly on the basis of ultrastructural morphology. They are usually green due to the dominance of pigments chlorophyll a and chlorophyll b. The chloroplast may be discoid, plate-like, reticulate, cup-shaped, spiral- or ribbon-shaped in different species. Most of the members have one or more storage bodies called pyrenoids located in the chloroplast. Pyrenoids contain protein besides starch. Some green algae may store food in the form of oil droplets. They usually have a cell wall made up of an inner layer of cellulose and outer layer of pectose.
Chlorophyta is a division of green algae informally called chlorophytes.
Volvox is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae. Volvox species form spherical colonies of up to 50,000 cells, and for this reason they are sometimes called globe algae. They live in a variety of freshwater habitats, and were first reported by Antonie van Leeuwenhoek in 1700. Volvox diverged from unicellular ancestors approximately 200 million years ago.
The Volvocaceae are a family of unicellular or colonial biflagellates, including the typical genus Volvox. The family was named by Ehrenberg in 1834, and is known in older classifications as the Volvocidae. All species are colonial and inhabit freshwater environments.
Gonium is a genus of colonial algae, a member of the order Chlamydomonadales. Typical colonies have 4 to 16 cells, all the same size, arranged in a flat plate, with no anterior-posterior differentiation. In a colony of 16 cells, four are in the center, and the other 12 are on the four sides, three each. A description by G.M. Smith :
Gonium Mueller 1773: Colonies of 4-8-16 cells arranged in a flat quadrangular plate and embedded in a common gelatinous matrix or connected by broad gelatinous strands. Cells ovoid to pyriform, with a single cup-shaped chloroplast containing one pyrenoid. Each cell with two cilia of equal length, contractile vacuoles at the base of the cilia, and an eyespot. Four- and eight-celled colonies with the cilia on the same side ; sixteen-celled colonies with the four central cells having their cilia on the same side and the twelve marginal cells with radially arranged cilia.
Asexual reproduction by simultaneous division of all cells in the colony to form autocolonies, or by a formation of 2-4 zoospores in each cell.
Sexual reproduction isogamous, by a fusion of biciliatezoogametes.
Chlamydomonadaceae is a family of algae within the order Chlamydomonadales. Traditionally, it has been defined as containing single-celled flagellates with a cell wall.
Oocystaceae is a family of green algae, in the order Chlorellales. The type genus is Oocystis.
The Tetrasporaceae are a family of green algae, specifically of the Chlamydomonadales. They are found in freshwater habitats.
Astrephomene is a genus of green algae in the family Goniaceae, order Chlamydomonadales. The genus was first described in 1937 by Pocock and named by Pockock in 1953. The genome of Astrephomene gubernaculifera has been sequenced.
Eudorina is a paraphyletic genus in the volvocine green algae clade. Eudorina colonies consist of 16, 32 or 64 individual cells grouped together. Each individual cell contains flagella which allow the colony to move as a whole when the individual cells beat their flagella together. Description by GM Smith :
Pleodorina is a genus of colonial green algae in the family Volvocaceae. Description by Gilbert M. Smith.
Pleodorina Shaw 1894:
Colonies always motile; spherical to sub-spherical, with 32-128 cells lying some distance from one another just within the periphery of the homogeneous, hyaline, gelatinous, colonial envelope and not connected by cytoplasmic strands. Cells differentiated into those that are purely vegetative in character and those capable of dividing to form daughter colonies. All but four cells of the colony reproductive or about half reproductive and half vegetative. Cells spherical to ovoid in shape. Vegetative cells with a cup-shaped chloroplast containing one pyrenoid; a large anterior eyespot; two cilia of equal length with two contractile vacuoles at their base. Reproductive cells at first like the vegetative cells, later with a more massive chloroplast that eventually contains several pyrenoids. The eyespot and cilia of reproductive cells disappearing when they are mature.
Asteromonas is a genus of green algae in the family Asteromonadaceae. It has been described from saline, marine, and brackish environments. It is closely related to the genus Dunaliella, another genus common in saline waters.
Carteria is a genus of green algae in the family Chlamydomonadaceae. Carteria are similar in morphology to the common genus Chlamydomonas and differ by having four, rather than two, flagella at the vegetative stage.
Chlainomonas is a genus of algae in the family Chlamydomonadaceae. They are found in freshwater habitats or on snow, where they are one of the main algae responsible for causing watermelon snow.
Chloromonas is a genus of green algae in the family Chlamydomonadaceae. It is closely related to the model green algae, Chlamydomonas, and traditionally has been distinguished mainly through the absence of a pyrenoid.
Pectodictyon is a genus of green algae in the family Sphaerodictyaceae. It is found free-floating in freshwater habitats as plankton.
Platydorina is a genus of microscopic green algae in the family Volvocaceae. It contains only one species, Platydorina caudata. It was described by Charles Atwood Kofoid in 1899.
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, it is not closely related to them; its sister is the unicellular genus Balticola.
Treubaria is a genus of green algae, the sole genus in the family Treubariaceae. Treubaria is found in freshwater habitats and has a cosmopolitan distribution.
Vitreochlamys is a genus of green algae in the family Chlamydomonadaceae. It is sometimes known by the name Sphaerellopsis, published by Aleksandr Arkadievich Korshikov. However, that name is an illegitimate later homonym, preceded by SphaerellopsisM.C.Cooke. It is commonly found in freshwater habitats.
