Staurastrum

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Staurastrum
Staurastrum paradoxum EPA.jpg
Staurastrum paradoxum
Scientific classification OOjs UI icon edit-ltr.svg
Clade: Viridiplantae
(unranked): Charophyta
Class: Zygnematophyceae
Order: Desmidiales
Family: Desmidiaceae
Genus: Staurastrum
Meyen ex Ralfs
Type species
Staurastrum paradoxum
Meyen ex Ralfs
Species

See text.

Staurastrum is a large genus of desmids (Desmidiaceae), [1] a group of green algae closely related to the land plants (Embryophyta). [2] [3] Members of this genus are microscopic and found in freshwater habitats around the world.

Contents

The name Staurastrum comes from the Greek roots stauron, meaning "cross", and astron, meaning "star". [4]

Description

Staurastrum consists of singular cells with two identical halves, called semicells; in most species, the cell is deeply constricted at the middle, making the division between semicells clear. When viewed from the polar axis, they are biradiate (with two planes of symmetry) or pluriradiate (with more than two planes of symmetry). [5] Biradiate individuals have long, arm-shaped extensions (termed "processes") attached to the main body of the semicells. Pluriradiate individuals may lack these processes. The cell wall is either smooth, or covered with granules or spines. In each semicell there is a chloroplast, usually located axially, with radiating lobes and/or ridges; some species have parietally located chloroplasts. [6]

Identification

Staurastrum as a genus is usually easy to identify, due to its long processes and symmetry. Some smaller species, particularly those without long processes, can be confused with Cosmarium , but that genus has biradiate (not pluriradiate) cells and never with long processes. The smaller species may also be confused with Tetraedron or various xanthophyte algae, but differ in shape, ornamentation, and chloroplast morphology. [5]

Although some species of Staurastrum are unmistakable, identification of species within the genus is often difficult. Important characters for identification include the degree of radiation (the number of planes of symmetry), overall shape and size of the cells, and the distribution and type of ornamentation on the cell wall. As with other genera of desmids, identification is complicated by the fact that these algae exhibit considerable phenotypic variability. [6]

Taxonomy

Staurastrum is the second largest genus of desmids (after Cosmarium), with about 800 species. It is the most heterogeneous desmid genus, and has been described as a wastebin taxon. [7] Several attempts have been made to dismantle the genus and split it up into smaller, more homogeneous units, such as G. M. Palamar-Mordvintseva's segregate genera Cylindriastrum, Cosmoastrum, and Raphidiastrum. These attempts have not been widely accepted, because they are also arbitrary. [8]

Staurastrum is not monophyletic, as molecular phylogenetic studies have shown that members of the genus are dispersed across many clades; however, a "core" Staurastrum clade was resolved. [9] The genus is still in use, because there is no known way of classifying desmids in line with their evolutionary history. [6]

Habitat and distribution

Staurastrum, as well as other desmid genera, live primarily in acidic lakes, ponds, and swamps with low nutrient levels. They usually live on sediments or submerged surfaces. A number of species are characteristic of eutrophic waters and are planktonic. [10]

Many species have a cosmopolitan distribution. [11] However, some species are restricted to a particular biogeographic realm. [12]

Species

Related Research Articles

<span class="mw-page-title-main">Zygnematales</span> Order of algae

The Zygnematales, also called the Conjugatales, are an order of green algae, comprising several thousand different species in two families. The larger family Zygnemataceae, with well-known genera such as Zygnema and Spirogyra, includes members that grow as unbranched filaments, which grow longer through normal cell division. This group includes the desmids. Most members of both families live in freshwater, and form an important component of the algal scum that grows on or near plants and rocks.

<span class="mw-page-title-main">Desmidiales</span> Order of algae

Desmidiales, commonly called the desmids, are an order in the Charophyta, a division of green algae in which the land plants (Embryophyta) emerged. Desmids consist of single-celled microscopic green algae. Because desmids are highly symmetrical, attractive, and come in a diversity of forms, they are popular subjects for microscopists, both amateur and professional.

<i>Euastrum oblongum</i> Species of alga

Euastrum oblongum is a species of desmid, in the family Desmidiaceae.

<i>Micrasterias</i> Genus of algae

Micrasterias is a unicellular green alga of the order Desmidiales. Its species vary in size reaching up to hundreds of microns.

<i>Chloromonas</i> Genus of algae

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.

<i>Lobomonas</i> Genus of algae

Lobomonas is a genus of green algae in the family Chlamydomonadaceae, found in freshwater habitats. Although it is widely distributed, it is a rare genus.

<span class="mw-page-title-main">Desmidiaceae</span> Family of algae

The Desmidiaceae are one of four families of charophyte green algae in the order Desmidiales (desmids).

<i>Closterium</i> Genus of algae

Closterium is a genus of desmid, a group of charophyte green algae. It is placed in the family Closteriaceae. Species of Closterium are a common component of freshwater microalgae flora worldwide.

<i>Cosmarium</i> Genus of algae

Cosmarium is a large genus of desmids (Desmidiaceae), a group of green algae closely related to the land plants (Embryophyta). Members of this genus are microscopic and found in freshwater habitats around the world.

<i>Desmidium</i> Genus of algae

Desmidium is a genus of green algae, specifically of the Desmidiaceae.

Spinoclosterium is a genus of green algae, specifically of the Closteriaceae. It is rare, but widely distributed in freshwater regions throughout the world.

<i>Staurodesmus</i> Genus of algae

Staurodesmus is a genus of green algae, specifically of the Desmidiaceae.

<i>Triploceras</i> Genus of algae

Triploceras is a genus of desmid in the family Desmidiaceae.

<i>Xanthidium</i> Genus of algae

Xanthidium is a genus of green algae, specifically of the Desmidiaceae.

<span class="mw-page-title-main">Zygnematophyceae</span> Class of algae

Zygnematophyceae is a class of green algae in the paraphylum streptophyte algae, also referred to as Charophyta, consisting of more than 4000 described species. The Zygnematophyceae are the sister clade of the Embryophyta.

Cosmarium tetragonum is a species of green algae in the family Desmidiaceae. It is a freshwater species with a worldwide distribution.

<i>Spirotaenia</i> Genus of algae

Spirotaenia is a genus of basal unicellular green algae that may be sister to the Chlorokybophyceae. It was previously considered to be part of the Zygnemataceae. It is sexually conjugating, a mode of reproduction that was previously only known in the Zygnemataceae/Mesotaeniaceae, the sister groups to the land plants. This is surprising, as Spirotaenia is much more basal. The conjugating process is substantially aberrant. Spirotaenia may actually be more than one distinct lineage which may not be closely related.

<i>Cosmarium botrytis</i> Species of alga

Cosmarium botrytis is a species of green algae in the family Desmidiaceae. It is a freshwater species with a worldwide distribution, and has been recorded from all continents.

Prescottiella is a genus of green algae in the family Desmidiaceae, containing the single species Prescottiella sudanensis. Originally classified as Micrasterias sudanensis in 1958, it was moved into its own genus by Carlos E. M. Bicudo in 1976, due to its asymmetric character. It is named after Gerald Webber Prescott, an American phycologist.

<i>Xanthidium antilopaeum</i> Species of desmid

Xanthidium antilopaeum is a species of unicellular desmid in the family Desmidiaceae. It is a common, worldwide species found in acidic waters, particularly the edges of large ponds and lakes.

References

  1. ↑ See the NCBI webpage on Staurastrum. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information . Retrieved 2007-03-19.
  2. ↑ Gontcharov AA, Marin BA, Melkonian MA (January 2003). "Molecular phylogeny of conjugating green algae (Zygnemophyceae, Streptophyta) inferred from SSU rDNA sequence comparisons". J. Mol. Evol. 56 (1): 89–104. doi:10.1007/s00239-002-2383-4. PMID   12569426.
  3. ↑ See the NCBI webpage on Cosmarium. Data extracted from the "NCBI taxonomy resources". National Center for Biotechnology Information . Retrieved 2007-03-19.
  4. ↑ Shayler, Hannah; Siver, Peter A. (2004). "Staurastrum". Carolina Lucid Key to Freshwater Algae. Connecticut College. Retrieved 2024-11-28.
  5. 1 2 Hall, John D.; McCourt, Richard M. (2014). "Chapter 9. Conjugating Green Algae Including Desmids". In Wehr, John D.; Sheath, Robert G.; Kociolek, J. Patrick (eds.). Freshwater Algae of North America: Ecology and Classification (2 ed.). Elsevier Inc. ISBN   978-0-12-385876-4.
  6. 1 2 3 Coesel, P.F.M.; Meesters, J. (2013). European flora of the desmid genera Staurastrum and Staurodesmus. Zeist: KNNV Publishing. p. 357. ISBN   978-90-04-27791-5.
  7. ↑ Teiling, Einar. "The genus Staurodesmus: A taxonomic study". Arkiv för Botanik. 6 (11): 467–629.
  8. ↑ Coesel, P.F.M.; Meesters, K.[J.]. Desmids of the Lowlands. 2nd revised & extended edition. Zeist: KNNV Uitgeverij. p. 424. ISBN   9789050119481.
  9. ↑ Gontcharov, Andrey A.; Melkonian, Michael (2005). "Molecular Phylogeny of Staurastrum Meyen ex Ralfs and Related Genera (Zygnematophyceae, Streptophyta) Based On Coding And Noncoding rDNA Sequence Comparisons". Journal of Phycology. 41 (4): 887–899. doi:10.1111/j.0022-3646.2005.04165.x.
  10. ↑ Coesel, Peter F. M.; Joosten, Anton M. T. (1996). "Three new planktic Staurastrum taxa (Chlorophyta, Desmidiaceae) from eutrophic water bodies and the significance of microspecies in desmid taxonomy". Algological Studies/Archiv für Hydrobiologie, Supplement Volumes. 80: 9–20. doi:10.1127/algol_stud/80/1996/9.
  11. ↑ Gerrath, Joseph F. (2003). "Conjugating Green Algae and Desmids". Freshwater Algae of North America. By Wehr, John D.; Sheath, Robert G. Elsevier Inc.
  12. ↑ Coesel, Peter F. M. (1996). "5. Biogeography of desmids". Hydrobiologia. 336 (1–3): 41–53. doi:10.1007/BF00010818. S2CID   11752270.
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