Compare

Gomphonema distans has narrower valves. Gomphonema lapponicum has a wider, and subrostrate headpole.

LM scalebar = 10 µm
Gomphonema nathorstii LM1 Gomphonema nathorstii LM2 Gomphonema nathorstii LM3 Gomphonema nathorstii LM4 Gomphonema nathorstii LM5 Gomphonema nathorstii LM6 Gomphonema nathorstii LM7
Length Range
30.8-49.6 µm
Width Range
7.8-9.9 near head pole; 8.3-10.0 at the valve center µm
Striae in 10 µm
10-13

Gomphonema distans

(A.Cleve) Lange-Bert. and E.Reichardt in Lange-Bert. and Genkal 1999

Gomphonema distans LM1 Gomphonema distans LM2 Gomphonema distans LM3 Gomphonema distans LM4 Gomphonema distans LM5 Gomphonema distans LM6 Gomphonema distans LM7
Length Range
26.1-45.6 µm
Width Range
6.0-7.2 at the valve center µm
Striae in 10 µm
9-13

Also compare to

Gomphonema lapponicum

(A.Cleve) A.Cleve