Compare Gomphonema amerhombicum
Gomphonema stoermeri valves are smaller in length and more rhombic in outline.
Gomphonema christensenii lacks an isolated stigmoid.
Gomphonema freesei is very similar in shape, size, stria density and overall appearance to G. amerhombicum under the light microscope.
Under critical illumination, Gomphonema freesei has coarse areolae. The ultrastructure of the striae of G. freesei, however, is unknown.
Gomphoneis rhombicum has a lower stria density (9.5-12 in 10 µm) and greater length to width ratio, that is, valves are more slender for their size (L = 35-53 µm, W = 4.5-7.5 µm). Note that G. rhombicum has not been verified in North America.
LM scalebar = 10 µm
Length Range
22.5-60 µm
22.5-60 µm
Width Range
5.6-7.7 µm
5.6-7.7 µm
Striae in 10 µm
13-15 at mid-valve, up to 17 at headpole
13-15 at mid-valve, up to 17 at headpole
Length Range
35.0-53.9 µm
35.0-53.9 µm
Width Range
6.5-7.5 µm
6.5-7.5 µm
Striae in 10 µm
12.1-14.5 at valve center, 14.2-16.2 at headpole, 11.7-15.4 at footpole
12.1-14.5 at valve center, 14.2-16.2 at headpole, 11.7-15.4 at footpole
Length Range
32.8-57.4 µm
32.8-57.4 µm
Width Range
6.1-7.8 µm
6.1-7.8 µm
Striae in 10 µm
13-16
13-16
Length Range
19-45 µm
19-45 µm
Width Range
4-6 µm
4-6 µm
Striae in 10 µm
13-15
13-15
