Cymbopleura tynnii

(Krammer) Krammer 2003      Category: Asymmetrical biraphid
BASIONYM: Cymbella pseudocuspidata Krammer 1978

REPORTED AS: Cymbella laterostrata var. alaskana (Patrick and Freese 1961, p. 263, plate 4, fig. 2) 

Cymbopleura subrostrata


Decussata placenta

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - September 2015
Length Range: 60-82 µm
Width Range: 15.7-18.6 µm
Striae in 10 µm: 10-13 near the valve center, up to 18 near the ends


Valves are broadly elliptic-lanceolate, with wide subrostrate apices. The axial area is narrow and close to the valve midline. The central area is a transverse rhomboid, sometimes asymmetric, and about 1/2 the valve width. The raphe is lateral, becoming filiform near the proximal and distal ends. Proximal raphe ends are somewhat inflated and bent towards the ventral side. Distal raphe ends are comma-shaped and deflected dorsally. Striae are radiate throughout and indistinctly punctate. Areolae number 28-30 in 10 µm.

Original Description

Basionym: Cymbella pseudocuspidata
Author: Krammer 1978
Length Range: 75 µm
Width Range: 18 µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Bahls, L. (2015). Cymbopleura tynnii. In Diatoms of the United States. Retrieved March 20, 2018, from

Species: Cymbopleura tynnii

Contributor: Loren Bahls

Reviewer: Teofil Nakov


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

Patrick, R.M. and Freese, L.R. (1961). Diatoms (Bacillariophyceae) from Northern Alaska. Proceedings of the Academy of Natural Sciences of Philadelphia 112(6):129-293.

Tynni, R. (1978). Über Finnlands rezente und subfossile Diatomeen, X. Geological Survey of Finland, Bulletin 296.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Cymbopleura tynnii CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

Krammer (2003) reports that this taxon prefers oligotrophic waters with low electrolyte content and lives as epiphytes on mosses. Its distribution is reported as from Alaska, Canada, Lapland, Spitsbergen and Siberia.


Small Lake, Coppermine Mountains, Nunavut, Canada: home of Cymbopleura tynnii.

Credit/Source: Beverly Boynton, Adventurers and Scientists for Conservation