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Navicula cryptocephala has rostrate apices and an evenly rounded central area. Navicula exilis has somewhat larger valves with protracted apices and a larger rounded central area.

LM scalebar = 10 µm
Navicula lundii LM7 Navicula lundii LM6 Navicula lundii LM5 Navicula lundii LM4 Navicula lundii LM3 Navicula lundii LM2 Navicula lundii LM1
Length Range
22-38 µm
Width Range
4.8-6.9 µm
Striae in 10 µm
14-18

Navicula cryptocephala

Kütz. 1844

Navicula cryptocephala LM4 Navicula cryptocephala LM6 Navicula cryptocephala LM2 Navicula cryptocephala LM7 Navicula cryptocephala LM5 Navicula cryptocephala LM1 Navicula cryptocephala LM3
Length Range
21-34 µm
Width Range
5.2-6.5 µm
Striae in 10 µm
15-17

Also compare to

Navicula exilis

Kütz. 1844