Compare

Gomphonema mexicanum has a higher stria density, more narrow apices and a lower L:W ratio. Gomphonema ventricosum has a broader axial area, especially at the central area, and higher stria striae at mid-valve. Gomphonema manubium is more robust, with a much broader axial area and higher areola density than G. mehleri. Gomphonema submehleri has a higher stria density and narrower valves than G. mehleri. Gomphonema gibba has a narrower headpole and less coarse stria. Note also, that similar but undescribed species, are present in the southeastern states.

LM scalebar = 10 µm
Gomp Mehleri 15551B 03232016 Uncounted Gomp1 03 Cl Gomp Mehleri 15592A 08202015 26 Cl Gomp Mehleri 15551A 12162015 03 Cl Gomp Mehleri 15551B 03232016 Uncounted Gomp1 02 Cl 53754A 20161206 01  Typespecimen Cl Gomp Mehleri 15551B2 03242016 08 Cl Gomp Mehleri 15551B2 03242016 07 Cl
Length Range
33-59 µm
Width Range
9.4-12.5 µm
Striae in 10 µm
7.5-9 at center; 11-12 at headpole; 12-13 at footpole

Gomphonema mexicanum

Grunow in Van Heurck 1880

Mexicanum 006 Mexicanum 001 Mexicanum 005 Mexicanum 002 Mexicanum 003 Mexicanum 004
Length Range
26-55 µm
Width Range
9-13 µm
Striae in 10 µm
9-11

Gomphonema ventricosum

W.Greg. 1856

Gomphonema ventricosum LM1 Gomphonema ventricosum LM5 Gomphonema ventricosum LM3 Gomphonema ventricosum LM4 Gomphonema ventricosum LM2
Length Range
33-47 µm
Width Range
10-12 µm
Striae in 10 µm
11-12

Gomphonema manubrium

Fricke 1904

Gomphonema manubrium LM6 Gomphonema manubrium LM5 Gomphonema manubrium LM1 Gomphonema manubrium LM7 Gomphonema manubrium LM3 Gomphonema manubrium LM2
Length Range
31.9-39.9 µm
Width Range
8.9-9.8 µm
Striae in 10 µm
11-14 in the center valve, 14-16 at the ends

Gomphonema gibba

J.H.Wallace 1960

Gomphonema Gibba 4356 A 1 Gomphonema Gibba 4356 A Girdle Gomphonema Gibba 4356 A 2 Gomphonema Gibba 4356 A 3 Gomphonema Gibba 4356 A 4 Gomphonema Gibba 4356 A 5
Width Range
7-8 µm
Striae in 10 µm
10-12 in the center valve, 12-14 at the ends

Gomphonema submehleri

Kociolek and Stoermer 1991

Gomphonema submehleri LM6 Gomphonema submehleri LM5 Gomphonema submehleri LM4 Gomphonema submehleri LM3 Gomphonema submehleri LM2 Gomphonema submehleri LM1
Length Range
24.9-37.2 µm
Width Range
5.2-7.8 µm
Striae in 10 µm
10-12 at the valve center, 14-16 at the head pole, 14-15 at the foot pole