Eunotia cataractarum belongs to the E. exigua complex based on size, striae density and valve constricted before the apices. The ventral margin of E. cataractarum is not as strongly concave as that of other members of E. exigua species complex. Furthermore, the apices of E. cataractarum are more rounded and not as strongly dorsally recurved compared with E. exigua. Finally, the shoulder is steeper in E. cataractarum valves compared with the more gradual slope in the E. exigua valves. While E. cataractarum is similar to E. varioundulata, the dorsal margin of E. caracatarum is flatter and lacks undulations. The dorsal margin of E. cataractarum is not straight as that of E. orthohedra.

LM scalebar = 10 µm
Eunotia cataractarum LM5 Eunotia cataractarum LM6 Eunotia cataractarum LM1 Eunotia cataractarum LM4 Eunotia cataractarum LM3 Eunotia cataractarum LM2 Eunotia cataractarum LM7
Length Range
11-21 µm
Width Range
3.1-3.9 µm
Striae in 10 µm
15-20 in the center valve, 16-19 at the ends, puncta 44-50

Eunotia orthohedra

Furey, Lowe and Johansen 2011

Eunotia orthohedra LM3 Eunotia orthohedra LM5 Eunotia orthohedra LM4 Eunotia orthohedra LM1 Eunotia orthohedra LM2
Length Range
12-19 µm
Width Range
2.7-3.8 µm
Striae in 10 µm
16-20 in the valve center, 20-22 at the ends

Also compare to

Eunotia exigua

(Bréb.) Rabh.

Eunotia varioundulata

Nörpel-Schempp and Lange-Bert.