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Navicula caterva is smaller and the areolae are not discernible. Navicula gregaria is larger and more lanceolate. Small specimens, however, of N. gregaria and N. canalis may easily be confused. Note that N. gregaria is relatively wider and the central area is more transapically expanded. Navicula namibica has a higher stria density (18-20 in 10 ┬Ám) and the central area is round.

LM scalebar = 10 µm
Navicula canalis LM6 Navicula canalis LM5 Navicula canalis LM3 Navicula canalis LM7 Navicula canalis LM4 Navicula canalis LM2 Navicula canalis LM1
Length Range
19.6-25 µm
Width Range
4.1-5.5 µm
Striae in 10 µm
16-19

Navicula caterva

M.H.Hohn and Hellerman 1963

Navicula caterva LM2 Navicula caterva LM1 Navicula caterva LM5 Navicula caterva LM8 Navicula caterva LM1 Navicula caterva LM3 Navicula caterva LM7
Length Range
14.8-20.0 µm
Width Range
4.4-5.0 µm
Striae in 10 µm
18-20

Navicula gregaria

Donkin 1861

Navicula gregaria LM4 Navicula gregaria LM5 Navicula gregaria LM3 Navicula gregaria LM7 Navicula gregaria LM6 Navicula gregaria LM2 Navicula gregaria LM1
Length Range
16-35 µm
Width Range
4.1-7.0 µm
Striae in 10 µm
14-18 in the center valve

Also compare to

Navicula namibica

Lange-Bert. and Rumrich