Gomphonema parvulum is smaller (10–36 μm long) with less strongly radiate striae. Gomphonema gracile lacks protracted apices and also has more weakly radiate striae. Valves of Gomphonema mexicanum are larger and lack the protracted headpole.

LM scalebar = 10 µm
Gomphonema johnsonii LM1 Gomphonema johnsonii LM2 Gomphonema johnsonii LM3 Gomphonema johnsonii LM4 Gomphonema johnsonii LM5 Gomphonema johnsonii LM6 Gomphonema johnsonii LM7
Length Range
24-50 µm
Width Range
6.9-8.5 µm
Striae in 10 µm
9-12 at the valve center, 14-18 near the apices

Gomphonema mexicanum

Grunow in Van Heurck 1880

Mexicanum 006 Mexicanum 001 Mexicanum 005 Mexicanum 002 Mexicanum 003 Mexicanum 004
Length Range
26-55 µm
Width Range
9-13 µm
Striae in 10 µm

Also compare to

Gomphonema gracile

Ehrenb. 1838

Gomphonema parvulum

(Kütz.) Kütz. 1849