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Eunotia metamonodon has a much smaller size range. It also has rounded apices and a lower proximal stria density (9-11 in 10 µm). Eunotia formica also has a much smaller size range. It has less curved valves, rounded apices, and lower proximal stria density (6-10 in 10 µm). Eunotia glacialifalsa differs by lower proximal stria density (8-11 in 10 µm) and round apices, but that taxon has not been verified in North America.

LM scalebar = 10 µm
Eutaut  Brant1212 337 45 6108 Eutautoniesis 1A Eutauntoniensis 2 Eutaut  Brant1006 Eutaut  Brant1188 Eutauntoniensis 5 Eutauntoniensis 6A
Length Range
97.2-337.5 µm
Width Range
6.4-8.9 µm
Striae in 10 µm
12-14 in the valve center, 14-16 at the ends

Eunotia metamonodon

Lange-Bert. 2011

Eu Mono 1 Eu Mono 2 Eu Mono 4 Eumono 9 Eu Mono 5 Eu Mono 7 Eu Mono 6
Length Range
26.3–246.0 µm
Width Range
9.6–16.7 µm
Striae in 10 µm
9–11 at center of the valve, 12–15 near the apices

Eunotia formica

Ehrenb. 1843

Eu Formica 1 Eu Formi 6 Eu Formi 2 Eu Formi 3 Eu Formi 4 Eu Formi 5
Length Range
51.8–142.1 µm
Width Range
6.4–9.9, at the central swelling: 7.8–15.8 µm
Striae in 10 µm
6–10 in the center, 10–16 near the apices

Also compare to

Eunotia glacialifalsa

Lange-Bert. 2000