(Krammer) Krammer 2003 Category: Asymmetrical biraphid
BASIONYM: Cymbella pseudocuspidata Tynnii 1978
REPORTED AS: Cymbella laterostrata var. alaskana (Patrick and Freese 1961, p. 263, plate 4, fig. 2)
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.
Basionym: Cymbella pseudocuspidata
Author: Tynnii 1978
Length Range: 75 µm
Width Range: 18 µm
Striae in 10 µm:
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.
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