| Atractomorpha | |
|---|---|
Scientific classification  | |
| (unranked): | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Chlorophyceae |
| Order: | Sphaeropleales |
| Family: | Sphaeropleaceae |
| Genus: | Atractomorpha L.Hoffman |
| Species | |
Atractomorpha is a genus in the Sphaeropleaceae, a family of green algae. [1] The genus name is derived from Greek and means "spindle-shaped" or "arrow-shaped", [2] and refers to the shape of the cells. [3]
Atractomorpha consists of solitary cells. Cells are variable in size, but range from 25 μm to 6 mm in length. They are usually spindle-shaped, with two sharply pointed ends, but sometimes may develop three- or four-pointed cells. Cells are initially uninucleate (with one cell nucleus), but as the cell develops it becomes multinucleate; the cytoplasm is separated by large vacuoles into zones each containing chloroplasts and nuclei. Chloroplasts are ring-shaped bands or diffusely net-like. [3]
Reproduction in Atractomorpha occurs asexually or sexually. In asexual reproduction, zoospores develop from vegetative cells, or less commonly aplanospores. Zoospores are relatively large, initially spindle-shaped but becoming pyriform or ovate. They are biflagellate but lose their flagella after setting, at which point they develop into vegetative cells. [3] In sexual reproduction, gametangia develop from vegetative cells; they may be separate male or female gametangia, or in one species, bisexual. [4] Male gametes are biflagellate, [3] and female gametes are biflagellate or non-flagellate, depending on the species. [5] The resulting zygotes from fertilization are initially surrounded by a thin membrane, later developing a thick wall and often an orange-red color. [3]
Two species of Atractomorpha are known, Atractomorpha echinata and Atractomorpha porcata . The two present similar vegetative cells, but can be distinguished by their reproductive characteristics. Individual cells of A. echinata typically produce either male or female gametes but not both, while cells A. porcata produces both male and female gametes. [5] Additionally, A. echinata is typically anisogamous while A. porcata is typically oogamous, and their zygote walls have different ornamentations. [5]
Atractomorpha has been recorded only a few times, mainly from soil isolates. [3] It occurs in shallow, temporary freshwater pools, and has been recorded from California, Texas, Australia, Namibia, [4] and Hungary. [6]
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.
Sphaeropleales is an order of green algae that used to be called Chlorococcales. The order includes some of the most common freshwater planktonic algae such as Scenedesmus and Pediastrum. The Sphaeropleales includes vegetatively non-motile unicellular, colonial, or filamentous taxa. They have biflagellate zoospores with flagella that are directly opposed in direction : Sphaeroplea, Atractomorpha, Neochloris, Hydrodictyon, and Pediastrum. All of these taxa have basal body core connections. Motile cells generally lack cell walls or have only a very fine layer surrounding the cell membrane. Other common characteristics include a robust vegetative cell wall, cup-shaped chloroplasts with large pyrenoids, and relatively large nuclei.
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.
In botany, a zoid or zoïd is a reproductive cell that possesses one or more flagella, and is capable of independent movement. Zoid can refer to either an asexually reproductive spore or a sexually reproductive gamete. In sexually reproductive gametes, zoids can be either male or female depending on the species. For example, some brown alga (Phaeophyceae) reproduce by producing multi-flagellated male and female gametes that recombine to form the diploid sporangia. Zoids are primarily found in some protists, diatoms, green alga, brown alga, non-vascular plants, and a few vascular plants. The most common classification group that produces zoids is the heterokonts or stramenopiles. These include green alga, brown alga, oomycetes, and some protists. The term is generally not used to describe motile, flagellated sperm found in animals. Zoid is also commonly confused for zooid which is a single organism that is part of a colonial animal.
Characiochloridaceae is a family of green algae in the order Chlamydomonadales.
The Characiosiphonaceae are a family of algae in the order Chlamydomonadales. Two genera are included in this family, Characiosiphon and Lobocharacium, each containing a single species. The genus Characiochloris may eventually be placed in this family pending future revisions, as it is phylogenetically closely related to the twose genera.
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.
Characiosiphon is a genus of green algae in the family Characiosiphonaceae. It contains a single species, Characiosiphon rivularis.
Chlamydopodium is a genus of green algae in the family Characiochloridaceae. It has been recorded from soil or attached to algae or zooplankton.
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.
Pseudomuriella is a genus of green algae, specifically of the class Chlorophyceae. It is the sole genus of the family Pseudomuriellaceae. It is a terrestrial alga that inhabits soils.
Sphaeroplea is a genus of green algae in the family Sphaeropleaceae. It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.
Trebouxia is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions. It can either exist in a symbiotic relationship with fungi in the form of lichen or it can survive independently as a free-living organism alone or in colonies. Trebouxia is the most common photobiont in extant lichens. It is a primary producer of marine, freshwater and terrestrial ecosystems. It uses carotenoids and chlorophyll a and b to harvest energy from the sun and provide nutrients to various animals and insects.
Spinoclosterium is a genus of green algae, specifically of the Closteriaceae. It is rare, but widely distributed in freshwater regions throughout the world.
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.
Allomyces is a genus of fungi in the family Blastocladiaceae. It was circumscribed by British mycologist Edwin John Butler in 1911. Species in the genus have a polycentric thallus and reproduce sexually or asexually by zoospores that have a whiplash-like flagella. They are mostly isolated from soils in tropical countries, commonly in ponds, rice fields, and slow-moving rivers.
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.
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