Pinnularia elegantoides differs by its swollen valve center and apices. P. guadalupensis has broader valves with wider a axial area. P. tenuistriata striae are parallel throughout entire valve. Varieties of P. subgibba with similar valve outlines have more rostrate/subcapitate/capitate apices and striae are radiate in the center. The granular axial area is unique to this species.

LM scalebar = 10 µm
Pinnularia feremorosa LM6 Pinnularia feremorosa LM1 Pinnularia feremorosa LM5 Pinnularia feremorosa LM7 Pinnularia feremorosa LM3 Pinnularia feremorosa LM4 Pinnularia feremorosa LM2
Length Range
59-79 µm
Width Range
8.0-8.7 µm
Striae in 10 µm

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

Also compare to

Pinnularia elegantoides


Pinnularia guadalupensis

Manguin in Bourrelly & Manguin 1952

Pinnularia tenuistriata

Hustedt in Schmidt et al. 1934