Compare

Gomphonema dichotomum is lanceolate-linear valve with predominantly concave sides, a smaller central area and lower stria density (9-11 in 10 µm). Gomphonema grasmueckii has very small central area, strongly radiate striae near the center and lower stria density (9-12 in 10 µm).

LM scalebar = 10 µm
Gomphonema californicum LM3 Gomphonema californicum LM1 Gomphonema californicum LM2 Gomphonema californicum LM4 Gomphonema californicum LM5 Gomphonema californicum LM6
Length Range
22-69 µm
Width Range
5.6-8.3 µm
Striae in 10 µm
10-15

Also compare to

Gomphonema dichotomum

Kütz. 1834

Gomphonema grasmueckii

Lange-Bert. and E.Reichardt 1993