name = Synurids
domain = Eukaryota
classis = Synurophyceae
classis_authority = Andersen, 1987
ordo = Synurales
ordo_authority = Andersen, 1987
subdivision_ranks = families
* SynuracaeeThe synurids are a small group of
heterokontalgae, found mostly in freshwater, which are covered in silicate scales and spines. These are formed on the surface of the chloroplasts, of which there are usually two, but sometimes only one divided into two lobes. The cells have two heterokont flagella, inserted parallel to one another at the anterior, whose ultrastructure is a distinguishing characteristic of the group. Both asexual and isogamous sexual reproduction occur.
There are two major genera included here, divided into species mainly based on the structure of the scales. "Mallomonas" are free-living individual cells, usually 50-100 μm in length. They have ornate scales and generally long spines. "Synura" occur as spherical colonies, with the cells oriented so that the flagella point outwards, each usually around 30 μm in length. The colonies are globular, rather than hollow, and spines are short if at all present. Both are common
planktonin lakes and ponds.
The synurids were originally included among the
golden algae in the order Ochromonadales as the family Mallomonadaceae. They were formally defined as a separate group by Andersenin 1987, who placed them in their own class Synurophyceae, based on an earlier suggestion by Cavalier-Smith.
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