| Asterococcus | |
|---|---|
 | |
| Asterococcus superbus | |
Scientific classification  | |
| (unranked): | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Chlorophyceae |
| Order: | Chlamydomonadales |
| Family: | Palmellopsidaceae |
| Genus: | Asterococcus Scherffel [1] |
| Species | |
See text | |
Asterococcus is a genus of green algae in the order Chlamydomonadales. [1] It is planktonic in freshwater ponds and lakes, or benthic within mires and swamps. It is a common and widespread genus, but is rarely abundant. [2]
The botanist Leon Cienkowski was the first to observed organisms now assigned to Asterococcus, when he described the taxon Pleurococcus superbus in 1865. Later in 1908, Aladár Scherffel transferred that species into a new genus, and named it Asterococcus. [3]
Asterococcus is monophyletic. Currently, taxonomic databases such as AlgaeBase place this genus in the family Palmellopsidaceae. However, molecular phylogenetics have demonstrated that it is most closely related to some species of Carteria , such as Carteria radiosa . [4]
Asterococcus consists of colonies in powers of two (two, four, eight, 16, rarely up to 64), or occasionally single cells, embedded within a conspicuous, often layered mucilaginous envelope. The cells are usually spherical to ellipsoidal and are either dispersed in the envelope or attached to the end of a branched (dendroid), mucilaginous stalk. Cells are 10–40 μm in diameter with smooth cell walls, a single nucleus and usually with two contractile vacuoles. Cells contain a single chloroplast in the center of the cell with a central pyrenoid, with numerous radiating lobes flattened against the cell wall. [2] [1]
Reproduction in Asterococcus occurs asexually by the formation of aplanospores or zoospores, of which two to eight are produced per cell. Once formed, they are released through the dissolution of the parent cell wall. Sexual reproduction has never been observed in this genus. [1]
There are currently five recognized species within the genus: [4]
Species identification in Asterococcus depends on morphological criteria such as the form of the colony (dendroid or not), characteristics of the cell wall, and whether the colonial envelope is lamellated or not. [4]
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.
Chlorococcaceae is a family of green algae, in the order Chlamydomonadales. They are mostly soil-dwelling algae. Many members of this group produce lipids and secondary carotenoids.
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.
Characiochloris is a genus of green algae in the family Characiochloridaceae. Characiochloris is epiphytic on freshwater algae, or found in soil.
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.
Chlamydocapsa is a genus of green algae, specifically of the Chlorophyceae.
Coelastropsis is a genus of green algae in the family Scenedesmaceae, containing the single species Coelastropsis costata. It is found in freshwater lakes and bogs, usually associated with mosses and filamentous algae. It has been recorded in Europe, Cuba and possibly New Zealand.
Cylindrocapsa is a genus of green algae, specifically of the Chlorophyceae. It is commonly found in freshwater habitats.
Dictyosphaerium is a genus of green algae, in the family Chlorellaceae. It occurs in freshwater habitats around the world and is planktonic.
Paulschulzia is a genus of green algae, specifically of the family Tetrasporaceae.
Pediastrum is a genus of green algae, in the family Hydrodictyaceae. It is a photoautotrophic, nonmotile coenobial green alga that inhabits freshwater environments.
Planktosphaeria is a genus of green algae, specifically of the Chlorophyceae. It was first described by the phycologist Gilbert Morgan Smith in 1918, with Planktosphaeria gelatinosa as its type species. Species of Planktosphaeria are commonly found in freshwater plankton around the world.
Quadrigula is a genus of green algae in the family Selenastraceae. It is commonly found in freshwater habitats as phytoplankton.
Sorastrum is a genus of green algae in the family Hydrodictyaceae. It is a component of the phytoplankton of freshwater ponds, lakes, and ditches. Sorastrum is common in tropical to temperate regions of the world, but due to its small size it is often overlooked.
Tetraspora is a genus of green algae in the family Tetrasporaceae of the order Chlamydomonadales, division Chlorophyta. Species of Tetraspora are unicellular green algae that exist in arrangements of four and consist of cells being packaged together in a gelatinous envelope that creates macroscopic colonies. These are primarily freshwater organisms, although there have been few cases where they have been found inhabiting marine environments and even contaminated water bodies. Tetraspora species can be found all around the globe, except in Antarctica. Despite the ubiquitous presence, the greatest growth of the genera's species is seen in the polar climatic zones.
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.
Deuterocharacium is a genus of green algae in the family Characiaceae. It is found in freshwater habitats, attached to algae or detritus. It is rare and has only been recorded from Europe.
Cecidochloris is a green algae genus in the family Chlorangiellaceae. It occurs in freshwater. However, it has only been reported so far from Europe, with an additional species from India that is incompletely described.
Apiocystis is a genus of algae belonging to the family Tetrasporaceae. It is found attached to freshwater aquatic algae or plants. The species of this genus are found in Europe and Northern America, and are widespread but generally uncommon.
Chlorangiella is a genus of microscopic algae, the type genus of the family Chlorangiellaceae. The name Chlorangiella was coined by Giovanni Battista de Toni in 1889. It is a nomen novum for Chlorangium F.Stein.