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This species is most easily confused with G. minuta, which is more widely distributed in North America. Gomphoneis herculeana valves are comparatively larger (length and width) than G. minuta as well as more strongly clavate in shape.

LM scalebar = 10 µm
Herculeana 001 Herculeana 004B Herculeana 004A Herculeana 006 Herculeana 002 Herculeana 003 Herculeana 005
Length Range
50-165 µm
Width Range
22-34 µm
Striae in 10 µm
8-12 in the central valve, 12-14 at the headpole, 13-16 at the footpole

Gomphoneis minuta

(J.L.Stone) Kociolek and Stoermer 1988

Minuta 005 Minuta 002 Minuta 001 Minuta 003 Minuta 004
Length Range
20-128 µm
Width Range
14-26 µm
Striae in 10 µm
10-12