Compare

Pinnularia subgibba has expanded valve margins.

Pinnularia procera can be difficult to separate, however it has narrower valves, (occasionally) undulate margins, and a broader fascia.

Pinnularia laxa has narrower valves, a higher stria density, and a broader fascia.

Pinnularia delicata has capitate apices and narrower valves.

Pinnularia rivularia has a lower stria density and larger valves.

LM scalebar = 10 µm
Pinnularia subgibba var. sublinearis LM1 Pinnularia subgibba var. sublinearis LM2 Pinnularia subgibba var. sublinearis LM4 Pinnularia subgibba var. sublinearis LM5 Pinnularia subgibba var. sublinearis LM3
Length Range
61-79 µm
Width Range
9-10 µm
Striae in 10 µm
9-10

Pinnularia subgibba

Krammer 1992

Pinnularia subgibba LM7 Pinnularia subgibba LM4 Pinnularia subgibba LM2 Pinnularia subgibba LM1 Pinnularia subgibba LM5 Pinnularia subgibba LM6 Pinnularia subgibba LM3
Length Range
63-127 µm
Width Range
11.7-13.6 µm
Striae in 10 µm
8-9

Also compare to

Pinnularia procera

Matzeltin and Krammer 1998

Pinnularia laxa

Hust. in Schmidt et al. 1934

Pinnularia delicata

(Freng.) Mills 1934

Pinnularia rivularis

Hust. 1935