Cymbopleura incertiformis var. laterostrata

Krammer 2003      Category: Asymmetrical biraphid

Cymbopleura incertiformis


Cymbopleura incertiformis var. linearis

LM scalebar = 10 µm = 80 pixels.


Contributor: Loren Bahls - January 2014
Length Range: 30-46 µm
Width Range: 5.9-6.9 µm
Striae in 10 µm: 16-18 at the valve center, about 20 at the ends on the dorsal side


Valves are linear-lanceolate and nearly symmetric, or barely dorsiventral. The margins are weakly convex to nearly parallel. Apices are subrostrate to broadly cuneate. The axial area is narrow and widens slightly near the central area. The central area is round, symmetric, and formed by shallow depressions on the dorsal and ventral sides. The raphe is lateral, becoming filiform toward the ends. Proximal raphe ends are not expanded and deflected ventrally. Distal raphe ends are hooked toward the dorsal side. Striae are radiate throughout and more widely spaced around the central area. Areolae are difficult to resolve in LM and number 30-34 in 10 µm.

Original Description

Author: Krammer 2003
Length Range: 24-60 µm
Width Range: 6.5-8.5 µm
Striae in 10 µm: 15-19 at the valve center, up to 20 towards the apices on the dorsal side

Original Description

Original Images

Cite This Page:
Bahls, L. (2014). Cymbopleura incertiformis. In Diatoms of the United States. Retrieved April 23, 2018, from

Species: Cymbopleura incertiformis

Contributor: Loren Bahls

Reviewer: Diane Winter


Krammer, K. (2003). Cymbopleura, Delicata, Navicymbula, Gomphocymbellopsis, Afrocymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 4: 1-530.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Cymbopleura incertiformis var. laterostrata CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

Together with the nominate variety, Krammer (2003) reports C. incertiformis var. laterostrata as “widely distributed in the subarctic, nordic, and alpine area in oligotrophic to dystrophic habitats with low electrolyte content”. Only one record is available from the Montana Diatom Collection: from Loudon Lake in Washington (photos below). Water quality data are not available for this site.


Loudon Lake, Okanogan County, Washington: home of Cymbopleura incertiformis var. laterostrata.

Credit/Source: Ryan Davis, Adventurers and Scientists for Conservation.

Closeup of gravelly bottom of Loudon Lake where C. incertiformis var. laterostrata was collected.

Credit/Source: Ryan Davis, Adventurers and Scientists for Conservation.