Surirella
Surirella is a genus of surirelloid diatoms which contains a wide variety of shapes and sizes. All Surirella have their raphe surround the cell at the perimeter of the valve margin. This robust raphe system allows them to be much more motile than many other diatom genera. One of the identifying features of almost all species of Surirella is that their valve faces contain costae, lines made up of rows of fine striae that are not easily visible with a light microscope. The costae are in turn grouped into units separated by fibulae, the wide and bold lines that are easily visible. These fibulae form a rib-like structure for the diatom.
1-2 lines of costae may be seen between the larger fibulae at the edge of a Surirella above.
S. angusta
-
Cells are 15.5-60 µm in length, 6.5-12 µm in width.
-
Rows of fibulae are 7-8 per 10 µm.
-
Longer specimens have parallel sides, while shorter species may have more outward-curved sides.
-
The shattered look is caused by a series of raised and lowered segments of costae.
For more information, visit diatoms.org here.
S. brebisonnii
-
Cells are 15.5-56 µm in length, 10-25 µm in width.
-
Rows of fibulae are 6-5 per 10 µm at the valve margin.
-
Cells have an exaggerated "egg"shape, broadly rounded at one end and more pointed at the other.
For more information, visit diatoms.org here.
S. tenera
-
Cells are 75-134.5 µm in length, 20-31.5 µm in width.
-
The rows present are not striae nor fibulae, but "porcae," undulations on the valve face that radiate away from the center. They range frm 18-26 per 100 µm.
-
One tip of the cell is wider and more rounded than the other, although it may be difficult to tell in some specimens due to the convex valve shape.
-
The raphe is situated along the perimeter of the valve face in a raised keel.
For more information, visit diatoms.org here.
Valve view
Girdle view