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Eucocconeis laevis

(Østrup) Lange-Bert. apud Lange-Bert. and Genkal in Lange-Bert. 1999      Category: Monoraphid
BASIONYM: Achnanthes laevis Østrup 1910

Eucocconeis flexella


Eunotia areniverma

LM scalebar = 10 µm = 80 pixels.


Contributor: Marina Potapova - December 2010
Length Range: 10-18 µm
Width Range: 5.4-7.1 µm
Striae in 10 µm: 25-35


Frustules are often strongly bent in the girdle view with concave raphe valve and convex rapheless valve. Valves are elliptical-lanceolate with slightly drawn-out ends. The raphe valve has a narrow axial area and an asymmetrical central area, which is usually expanded to the valve margin on one side. The raphe is straight or slightly sigmoid with terminal ends sharply turned to opposite directions. Rapheless valve has a narrow linear or slightly sigmoid axial area and a large central area of variable shape, often asymmetrical an expanded to one or both valve margins. Sometimes a shallow depression is visible on one side of the central area. The striae are radiate, 25-35 in 10 μm.

Note that this concept of E. laevis is wide and includes types of E. quadratarea (Ostrup) Lange-Bertalot in Lange-Bertalot and Genkal, E. diluviana (Hustedt) Lange-Bertalot in Lange-Bertalot and Genkal, and E. lapponica Hustedt. North American researchers have referred this taxon to Achnanthes lapponica var. ninckei (Guerm. and Mang.) Reimer [Syn.: Eucocconeis lapponica var. ninckei (Guerm. and Mang.) Stoermer and Yang 1969] based on its treatment in Patrick and Reimer (1966). Further investigation is necessary to establish whether these taxa represent separate species.

Original Description

Basionym: Achnanthes laevis
Author: Østrup 1910
Length Range: 13 µm
Width Range: 5.5 µm
Striae in 10 µm:

Original Description

Long. 13 μ, Lat. 5,5 μ. Striis subtilissimis. Valva elliptica, apicibus subtruncatis. Epitheca: Area apicali angusta, lineari. Striis inconspicuis. Hypotheca: Raphe area apicali hyalina, angustissima, media in parte valvæ subito dilatata, cincta. Striis media modo in parte valvæ conspicuis.

Original Images

Cite This Page:
Potapova, M. (2010). Eucocconeis laevis. In Diatoms of the United States. Retrieved May 22, 2018, from

Species: Eucocconeis laevis

Contributor: Marina Potapova

Reviewer: Mark Edlund


Lange-Bertalot, H. and Genkal, S.I. (1999). Diatoms from Siberia I. Islands in the Arctic Ocean (Yugorsky-Shar Strait). Iconographia Diatomologica 6: 1-292.

Østrup, E. (1910). Danske Diatoméer. C.A. Reitzels Boghandel, Kjøbenhavn. 323 pp., 5 pls.

Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Stoermer, E. F. and Yang, J. J. (1969). Plankton diatom assemblages in Lake Michigan. Univ. Michigan, Great Lakes Res. Div. Spec. Rep. No. 47, 168 pp.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Eucocconeis laevis CAS

NCBI Genbank Taxonomy

Eucocconeis laevis NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 187002

Autecology Discussion

EMAP Assessment

The Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Over 1200 streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.

EMAP Distribution

Eucocconeis laevis

EMAP Response Plots

Eucocconeis laevis

EMAP citations

Results are published in:

Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.

Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.

Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.