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Diatoms of the United States is now known as Diatoms of North America.
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Gomphoneis septa

(Moghadam) Kociolek, Stoermer and L.L.Bahls 1986      Category: Asymmetrical biraphid
BASIONYM: Gomphonema septum Moghadam 1969

Gomphoneis pseudo-okunoi


Gomphoneis trullata

LM scalebar = 10 µm = 40 pixels.


Contributor: Pat Kociolek - February 2011
Length Range: 34-90 µm
Width Range: 11-15 µm
Striae in 10 µm: 11-12 at the center, 14-16 at the poles


Valves lanceolate-clavate, with headpole rounded and slightly protracted. Footpole rounded. Valve tapers gently towards the headpole, more strongly towards the footpole, especially in shorter specimens. The raphe is undulate and lateral. The axial area is narrow at the poles, straight, widens at the center to form a small, somewhat rounded central area. A single round stigma is found in the central area. Striae are radiate throughout the length of the valve. Longitudinal lines are positioned on either side of the axial area; they are indistinct in some specimens. The apical pore field is small. This species is known only from Montana.

Comments: These metrics for length and breadth indicates valves can be slightly smaller (down to 34 µm in length, and 11 µm in breadth) than indicated in Kociolek et al. (1986)

Original Description

Basionym: Gomphonema septum
Author: Moghadam 1969
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Kociolek, P. (2011). Gomphoneis septa. In Diatoms of the United States. Retrieved May 25, 2018, from

Species: Gomphoneis septa

Contributor: Pat Kociolek

Reviewer: Rex Lowe


Kociolek, J.P., Stoermer, E.F. and Bahls, L.L. (1986). Observations on North America Gomphoneis III. Gomphoneis septa comb. nov. Canadian Journal of Biology 64(11):2764-2768.

Moghadam, F. (1969). An ecological and systematic study of the planktonic diatom communities in Flathead Lake, Montana. Proceedings of the Academy of Natural Sciences of Philadelphia 121: 153-228.

Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Gomphoneis septa CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion