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Species within the Eunotia praerupta - Eunotia bidens group also possess slight dorsal undulations. 

Eunotia inflata has a rounded dorsal margin.

Eunotia superbidens has dorsally recurved ends. 

Eunotia richbuttensis valves are more narrow and consistently possess one apical rimoportula.

LM scalebar = 10 µm
Eunotia richbuttensis LM1 Eunotia richbuttensis LM2 Eunotia richbuttensis LM3 Eunotia richbuttensis LM4 Eunotia richbuttensis LM5 Eunotia richbuttensis LM6
Length Range
20-59 µm
Width Range
7.3-9.9 µm
Striae in 10 µm
10-14 at the center of the valve, 12-16 at the ends

Eunotia bidens

Ehrenb. 1943

Eunotia bidens LM1 Eunotia bidens LM2 Eunotia bidens LM3 Eunotia bidens LM4 Eunotia bidens LM5 Eunotia bidens LM6 Eunotia bidens LM7
Length Range
46.7-60.0 µm
Width Range
at the valve center: 8.5-10.5 µm
Striae in 10 µm
9-12 in the valve center, 12-15 at the ends

Eunotia superbidens

Lange-Bert. 2011

Eunotia superbidens LM1 Eunotia superbidens LM2 Eunotia superbidens LM3 Eunotia superbidens LM4 Eunotia superbidens LM5 Eunotia superbidens LM6 Eunotia superbidens LM7
Length Range
23.3-111.2 µm
Width Range
at the valve center: 11.4-16.7 µm
Striae in 10 µm
7-11 in the valve center, 12-14 at the ends.

Also compare to

Eunotia praerupta

BioData Reference
Krammer and Lange-Bertalot 2/3 Pl 148 Fig 1-3

Eunotia inflata

(Grunow) Nörpel-Schempp and Lange Bert.