The synurids (order Synurales) are a small group of

heterokont The stramenopiles, also called heterokonts, are protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, an ...

algae, found mostly in

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

environments, characterized by cells covered in

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

scales.

Characteristics

They are covered in silicate scales and spines. In ''Synura'', these are formed on the surface of the

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s, two of which are usually present, but sometimes only one divided into two lobes is seen. The cells have two heterokont

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

, inserted parallel to one another at the anterior, whose ultrastructure is a distinguishing characteristic of the group. Both asexual and isogamous sexual reproduction occur.

Morphology

center, upright=2,

Classification

Synurales are divided into three families, each with one genus: * Family Mallomonadaceae ** ''Mallomonas'' * Family Synuraceae">Mallomonas.html" ;"title="Mallomonadaceae ** ''Mallomonas">Mallomonadaceae ** ''Mallomonas'' * Family Synuraceae ** ''Synura'' * Family Neotessellaceae ** ''Neotessella'' (=''Tessella'' )

History

The genus ''Synura'' was proposed in 1834 by the German microscopist Christian Gottfried Ehrenberg (1795–1876). The synurids were originally included among the

golden alga The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae, or golden algae, are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer to a single species, '' Prymnesium parvum'', wh ...

e in the order

Ochromonadales Ochromonadales is an order of single-celled algae belonging to the class Chrysophyceae, also known as golden algae. Initially it contained numerous groups of flagellates that were not closely related. During the late 20th century, advancements i ...

as the family Mallomonadaceae or as the family Synuraceae . They were formally defined as a separate group by Andersen in 1987, who placed them in their own class Synurophyceae, based on an earlier approach of more narrowly defining major lineages of chrysophyte algae by British phycologist David Hibberd. The

Chrysophyceae The Chrysophyceae, usually called chrysophytes, chrysomonads, golden-brown algae, or golden algae, are a large group of algae, found mostly in freshwater. Golden algae is also commonly used to refer to a single species, '' Prymnesium parvum'', wh ...

and Synurophyceae are currently recognized as closely related taxa within the

Stramenopile The stramenopiles, also called heterokonts, are protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, an ...

s. Present classifications include the synurids as an order (Synurales) within

References

External links

Chrysophyceae {{Heterokont-stub