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Compare Fragilariforma nitzschioides

(Grunow) Lange-Bert. 2011

Compare

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
Fragilariforma nitzschioides LM3 Fragilariforma nitzschioides LM4 Fragilariforma nitzschioides LM5 Fragilariforma nitzschioides LM6 Fragilariforma nitzschioides LM2 Fragilariforma nitzschioides LM1 Fragilariforma nitzschioides LM7
Length Range
19-54 µm
Width Range
3.5-5.5 µm
Striae in 10 µm
18-25

Fragilariforma virescens

(Ralfs) D.M.Williams and Round 1988

Fragilariforma virescens LM6 Fragilariforma virescens LM3 Fragilariforma virescens LM1 Fragilariforma virescens LM4 Fragilariforma virescens LM2 Fragilariforma virescens LM5
Length Range
15-60 µm
Width Range
6.5-7.0 µm
Striae in 10 µm
20-22

Stauroforma exiguiformis

(Lange-Bert.) Flower, Jones and Round 1996

Stauroforma exiguiformis LM4 Iwb 0040 06072015 08 Cl Stauroforma exiguiformis LM1 Stauroforma exiguiformis LM3 Stauroforma exiguiformis LM5 Stauroforma exiguiformis LM2
Length Range
4-22 µm
Width Range
3-4 µm
Striae in 10 µm
16-20