Compare

Gomphonema carolinense is larger, heteropolar and more clavate-elliptic. The Gomphonema parvulum-complex has narrower valves with more clavate-elliptic forms (e.g. G. parvulum var. lagenula Frenguelli) and parallel to only slightly radiate striae.

LM scalebar = 10 µm
Gomphonema montezumense LM7 Gomphonema montezumense LM6 Gomphonema montezumense LM5 Gomphonema montezumense LM4 Gomphonema montezumense LM3 Gomphonema montezumense LM2 Gomphonema montezumense LM1
Length Range
12.2-19.8 µm
Width Range
8.9-11.9 µm
Striae in 10 µm
11.2-14.5

Also compare to

Gomphonema carolinense

Hagelst.

Gomphonema parvulum

Kütz.