Home / Diatoms / Pennate / Unicells / Biraphes / Asymmetric / Keeled / Surirella
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Name derivation:
Classification:
Surirella Turpin 1828; 196 of 1228 species names are currently accepted taxonomically (Guiry and Guiry 2014). Order Surirellales; Family Surirellaceae
Morphology:
Solitary elliptical cells can be isopolar (two opposite ends that are alike in shape) or heteropolar (two opposite ends that are not alike in shape). Cells can be elongated or elliptical and can be slightly constricted or twisted at the middle. In valve view, the raphe system runs around the perimeter of the frustule that is raised on a keeled edge. The valve face can be either flat or slightly concave towards the middle with undulations moving inward. The cell can be ornamented with siliceous bumps or ridges. The keel is highly visible in girdle view. Generally contains one plastid with two valve appressed plates that are connected by a narrow silica bridge near one end of the cell. In a heteropolar species it appears near the narrowest of the two ends.
Similar genera:
Some cells with constrictions in the center can appear similiar to Cymatopleura. They differ in that the valve face of Surirella has undulating striations that point inwards to the center of the cell. Surirella often has siliceous bumps or ridges on the valve face unlike Cymatopleura.
Habitat:
Can be found in both freshwater and marine habitats and in an epipelic genus.
References:
Round, F. E., Crawford, R. M., Mann, D. G. 1990. The Diatoms. Cambridge University Press. New York, NY. Smith, Gilbert, 1950. The Fresh-Water ALgaie of the United States. McGraw-Hill Book Company, Inc. New York, NY.