Compare

Pinnularia alpina has larger elliptic valves (> 38 µm wide) with lanceolate axial areas. Pinnularia rabenhorstii has smaller valves (< 18 µm wide) and subrostrate apices. Pinnularia borealis has smaller valves (< 10 µm wide) and 5-6 striae in 10 µm.

LM scalebar = 10 µm
Pinnularia lata LM6 Pinnularia lata LM11 Pinnularia lata LM5 Pinnularia lata LM10 Pinnularia lata LM12 Pinnularia lata LM13
Length Range
80.2-127.6 µm
Width Range
23.2-28.7 µm
Striae in 10 µm
3-4

Pinnularia rabenhorstii

(Grunow) Krammer 2000

Pinnularia rabenhorstii LM1 Pinnularia rabenhorstii LM2 Pinnularia rabenhorstii LM3 Pinnularia rabenhorstii LM4 Pinnularia rabenhorstii LM5 Pinnularia rabenhorstii LM6 Pinnularia rabenhorstii LM7
Length Range
49.6-71.1 µm
Width Range
12.1-17.9 µm
Striae in 10 µm
4-5

Pinnularia borealis

Ehrenb. 1843

Pinnularia borealis LM7 Pinnularia borealis LM6 Pinnularia borealis LM5 Pinnularia borealis LM4 Pinnularia borealis LM3 Pinnularia borealis LM2 Pinnularia borealis LM1
Length Range
27.1-47.6 µm
Width Range
8.0-10.2 µm
Striae in 10 µm
5-6

Also compare to

Pinnularia alpina

W.Sm. 1853