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Gomphonema apicatum is more apiculate, and broader than either G. acuminatum or G. coronatum, two taxa with which it has been confused.

LM scalebar = 10 µm
Gomphonema apicatum LM1 Gomphonema apicatum LM2 Gomphonema apicatum LM5 Gomphonema apicatum LM4 Gomphonema apicatum LM3
Length Range
40-53 µm
Width Range
13-15 (as measured at the broadest portion of the valve) µm
Striae in 10 µm
9-11

Gomphonema acuminatum

Ehrenb. 1832

Gomphonema Acuminatum 002 Gomphonema Acuminatum 001 Gomphonema Acuminatum 003 Gomphonema Acuminatum 005 Acuminatum Gc109928B004 Gomphonema Acuminatum 004
Length Range
19-77 µm
Width Range
7-12 µm
Striae in 10 µm
9-12 at the center, 12-14 towards the footpole

Gomphonema coronatum

Ehrenb. 1840

Coronatum Gc4367A006 Coronatum Gc4367A007 Coronatum Gc4367A003 Coronatum Gc1283004 Coronatum Gc1283002 Coronatum Gc1283001
Length Range
34-108 µm
Width Range
8-13 µm
Striae in 10 µm
8-12, approaching 15/10 ┬Ám at the footpole