Cymbella cymbiformis

Agardh 1830      Category: Asymmetrical biraphid

REPORTED AS: Cymbella cymbiformis (Patrick and Reimer 1975, Plate 10, fig. 3 [not fig. 4]) 

Cymbella cosleyi


Cymbella designata

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - May 2016
Length Range: 76-121 µm
Width Range: 17.0-20.1 µm
Striae in 10 µm: 6-9 at the valve center, up to 15 near the apices


Valves are lanceolate and dorsiventral with bluntly rounded apices. The dorsal margin is moderately arched; the ventral margin is weakly concave with a slightly gibbous middle. The axial area is linear. The central area is small and elliptic, somewhat wider on the ventral side. The raphe is distinctly lateral, becoming reverse-lateral near the proximal ends. Proximal raphe ends are deflected ventrally and terminate with inflated pores. Terminal raphe fissures are deflected ventrally at about 45 degrees. Striae are widely spaced and nearly parallel at the valve center, becoming radiate near the apices. Areolae are distinct in LM and widely spaced, numbering 14-17 in 10 µm. Stigmata are variable in number. Usually there are 1 or 2 on the ventral side of the central nodule.

Note that the width of the specimens illustrated here not conform with the width of European C. cymbiformis (Krammer 2002). Further work may show this North American taxon to be a different species.

Original Description

Author: C.Agardh 1830
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Bahls, L. (2016). Cymbella cymbiformis. In Diatoms of the United States. Retrieved April 22, 2018, from

Species: Cymbella cymbiformis

Contributor: Loren Bahls

Reviewer: Marina Potapova


Agardh, C.A. (1830). Conspectus Criticus Diatomacearum. Part 1. Lundae. Litteris Berlingianis. pp. 1-16.

Krammer, K. (2002). The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584.

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)

Original INA

California Academy of Sciences (CAS)

Cymbella cymbiformis CAS

NCBI Genbank Taxonomy

Cymbella cymbiformis NCBI

North American Diatom Ecological Database (NADED)


Autecology Discussion

The specimens of C. cymbiformis shown on this web page were collected from Lake Winona, a shallow lake with abundant submerged and emergent vegetation on the west side of Glacier National Park, Montana (photos below). At the time of collection, Lake Winona had a pH of 7.20 and electrical conductance of 250 µS/cm. Krammer (2002) reports this species as widely distributed in arctic, subarctic, and temperate regions, primarily in the littoral zones of oligotrophic lakes and streams with low to very low electrolyte content.


Lake Winona, Glacier National Park, Montana: home of Cymbella cymbiformis

Credit/Source: Billy Schweiger, National Park Service

Closeup of Lake Winona shoreline, Glacier National Park, Montana: home of Cymbella cymbiformis

Credit/Source: Billy Schweiger, National Park Service