| Sphaeroplea | |
|---|---|
 | |
| Sphaeroplea annulina | |
Scientific classification  | |
| (unranked): | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Chlorophyceae |
| Order: | Sphaeropleales |
| Family: | Sphaeropleaceae |
| Genus: | Sphaeroplea C.Agardh |
| Species | |
See text | |
Sphaeroplea is a genus of green algae in the family Sphaeropleaceae. [1] It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824. [2]
Sphaeroplea consists of unbranched filaments of cells, one cell thick. Cells are usually 10–50 μm in diameter, but one variety can reach up to 170 μm in diameter. Cells are cylindrical, several times longer than wide, with a linear series of alternating vacuoles and cytoplasmic zones containing nuclei and chloroplasts. The chloroplasts are band-shaped, and contain several pyrenoids. Nuclei are typically in pairs. [2] [3]
Sphaeroplea reproduces asexually and sexually. In asexual reproduction, the filaments break apart, although one species has been observed to produce zoospores that are biflagellate (i.e. with two flagella). [4] Sexual reproduction is typically oogamous, where vegetative cells become reproductive cells without changing their shape. [3] Female gametes are large, spherical and green, and are borne in one to several rows within the cell. Male gametes are typically produced on the same filament as female gametes, and are small and biflagellate. [2]
After the gametes fuse, a zygote (termed an oospore) is formed. Zygotes develop a thick cell wall with ornamentation, and eventually turn reddish-orange before being released. The zygotes may last for an extended period of time in a desiccated state. During germination, the zygote becomes four biflagellate cells that attach to a substrate, lose their flagella, and develop into a new filament. [2]
Sphaeroplea occurs in temporary freshwater habitats such as roadside ditches, margins of ponds, and vleis. It tends to prefer calcareous habitats. It has been recorded from all continents except Antarctica, but not very frequently. Its occurrence is ephemeral; it tends to appear abundantly in one spot, then disappear for many years. [2] When abundant, it can impart a reddish discoloration to the water with its abundant reddish-orange oospores. [3]
According to AlgaeBase, the following species are accepted: [2]
One fossil species is known:
Species are distinguished from each other by characteristics of the oospores, such as their shape and ornamentation. [3]
Chlamydomonadales, also known as Volvocales, are an order of flagellated or pseudociliated green algae, specifically of the Chlorophyceae. Chlamydomonadales can form planar or spherical colonies. These vary from Gonium up to Volvox. Each cell has two flagella, and is similar in appearance to Chlamydomonas, with the flagella throughout the colony moving in coordination.
The water net is a taxon of freshwater green algae in the family Hydrodictyaceae. Hydrodictyon does well in clean, eutrophic water, and has become a nuisance in New Zealand, where it has been recently introduced. The name water net comes from the mesh structure of their colonies, which can extend several decimeters.
Ulothrix is a genus of green algae in the family Ulotrichaceae.
Bryopsidales is an order of green algae, in the class Ulvophyceae.
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 species common in saline waters.
Atractomorpha is a genus in the Sphaeropleaceae, a family of green algae. The genus name is derived from Greek and means "spindle-shaped" or "arrow-shaped", and refers to the shape of the cells.
Brachiomonas is a genus of thalloid biflagellate green algae. These algae generally are found in marine or brackish waters, but can tolerate wide range of salinities. They may occur in freshwater pools near the sea and, occasionally, in polluted inland freshwater habitats.
Characiochloris is a genus of green algae in the family Characiochloridaceae. Characiochloris is epiphytic on freshwater algae, or found in soil.
Characiosiphon is a genus of green algae in the family Characiosiphonaceae. It contains a single species, Characiosiphon rivularis.
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.
Lobocharacium is a genus of green algae in the family Characiosiphonaceae. It contains the single species Lobocharacium coloradoense. It has been isolated from a pond in Colorado, United States.
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.
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.
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.
Spinoclosterium is a genus of green algae, specifically of the Closteriaceae. It is rare, but widely distributed in freshwater regions throughout the world.
Actinochloridaceae is a family of green algae, in the order Chlamydomonadales.
Chlorotetraedron is a genus of green algae, in the family Neochloridaceae. The name may also be written as Chlorotetraëdon. It is found as freshwater plankton or in soil.
Korshikoviella is a genus of green algae in the family Characiaceae.
Scytothamnus australis is a brown alga species in the genus Scytothamnus found in New Zealand. It is a sulphated polysaccharide and the type species in the genus.
Bracteamorpha is a genus of green algae in the order Sphaeropleales, and is the only genus in the family Bracteamorphaceae. It contains a single species, Bracteamorpha trainorii.
