Compare Fragilariforma nitzschioides
Fragilariforma nitzschioides can be distinguished from F. virescens by the shape of the apices, stria density and the shape in girdle view. The apices of F. nitzschioides are only slightly rostrate, or more commonly, bluntly rounded, whereas the apices of F. virescens are distinctly rostrate. In girdle view, F. nitzschioides can be distinguished from F. virescens based on the more rectangular shape of the frustule, the presence of small connecting spines, striae that continue well onto the mantle and the fewer number of girdle bands (2-3 in F. nitzschioides compared with 4-6 in F. virescens). Stauroforma exiguiformis lacks rimoportulae and a clear central sternum; the striae appear to extend over the entire valve face.
LM scalebar = 10 µm
Length Range
19-54 µm
19-54 µm
Width Range
3.5-5.5 µm
3.5-5.5 µm
Striae in 10 µm
18-25
18-25
Length Range
15-60 µm
15-60 µm
Width Range
6.5-7.0 µm
6.5-7.0 µm
Striae in 10 µm
20-22
20-22
Length Range
4-22 µm
4-22 µm
Width Range
3-4 µm
3-4 µm
Striae in 10 µm
16-20
16-20
