Compare

Pinnularia brevicostata is larger (up to 150 ┬Ám) and lacks the gibbous center and mottled valve surface. Pinnularia cuneicephala has cuneate apices and a sinuous outer fissure of the raphe. Pinnularia nobilis is much larger with convergent striae near the apices.

LM scalebar = 10 µm
Pinnularia acrosphaeria LM7 Pinnularia acrosphaeria LM6 Pinnularia acrosphaeria LM5 Pinnularia acrosphaeria LM4 Pinnularia acrosphaeria LM3 Pinnularia acrosphaeria LM2 Pinnularia acrosphaeria LM1
Length Range
52.7-82.9 µm
Width Range
9.7-12.0 µm
Striae in 10 µm
11-13

Pinnularia cuneicephala

(A.Mann) R.M.Patrick 1966

Pinnularia cuneicephala LM4 Pinnularia cuneicephala LM6 Pinnularia cuneicephala LM1 Pinnularia cuneicephala LM8 Pinnularia cuneicephala LM5 Pinnularia cuneicephala LM7 Pinnularia cuneicephala LM2
Length Range
79-142 µm
Width Range
14-19 µm
Striae in 10 µm
6-7

Also compare to

Pinnularia brevicostata

Cleve 1891

Pinnularia nobilis

(Ehrenb.) Ehrenb. 1843