Cymbella excisiformis and C. cosleyi both have a less exaggerated arcuate outline.

Cymbella botellus is smaller.

LM scalebar = 10 µm
Length Range
25-46 µm
Width Range
6.4-8.3 µm
Striae in 10 µm
8.5-10
Cymbella cleve-eulerae LM1
Cymbella cleve-eulerae LM2
Cymbella cleve-eulerae LM3
Cymbella cleve-eulerae LM4
Cymbella cleve-eulerae LM5
Cymbella cleve-eulerae LM6
Cymbella cleve-eulerae LM7
Cymbella cleve-eulerae LM1 Cymbella cleve-eulerae LM2 Cymbella cleve-eulerae LM3 Cymbella cleve-eulerae LM4 Cymbella cleve-eulerae LM5 Cymbella cleve-eulerae LM6 Cymbella cleve-eulerae LM7
Length Range
24-34 µm
Width Range
6.1-7.1 µm
Striae in 10 µm
9-11 in the center valve, 12-16 at the ends
Cymbella excisiformis LM5 Cymbella excisiformis LM2 Cymbella excisiformis LM1 Cymbella excisiformis LM3 Cymbella excisiformis LM4 Cymbella excisifomis LM7 Cymbella excisifomis LM6

Cymbella cosleyi

Bahls 2013

Length Range
20-31 µm
Width Range
5.5-7.1 µm
Striae in 10 µm
10-12 at the valve center, 14-16 near the apices
Cymbella cosleyi LM1 Cymbella cosleyi LM2 Cymbella cosleyi LM3 Cymbella cosleyi LM4 Cymbella cosleyi LM5 Cymbella cosleyi LM6 Cymbella cosleyi LM7

Also compare to

Cymbella botellus

(Lagerst.) Schmidt 1881