Compare

Gomphonema affine is more narrow, elongate, and lacks septa and pseudosepta.

LM scalebar = 10 µm
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
9-11

Also compare to

Gomphonema affine

Kutz.