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Navicula symmetrica

R.M.Patrick 1944      Category: Symmetrical biraphid

Navicula supleeorum


Navicula trilatera

LM scalebar = 10 µm = 80 pixels.


Contributor: Kalina Manoylov | Paul Hamilton - June 2010
Length Range: 24-35 µm
Width Range: 5-6.5 µm
Striae in 10 µm: 12-17


Valves are linear-elliptical to linear-lanceolate with narrow, rounded apices. Valves are 24.0-34.5 µm long and 5.0-6.5 µm wide. Striae are 12-17 in 10 µm. The axial area is narrow and linear and the central area is asymmetrically rounded. The raphe is filiform with enlarged proximal raphe ends that weakly unilaterally deflected. The distal raphe fissures are distinctly deflected from the valve face onto the mantle, with the deflection to the secondary side. The lineolate striae are strongly radiate at the center and radiate throughout the valve. The space between each stria is equal or wider to the width of the stria. Voigt faults are often evident on the secondary side of the valve. Areolae are 24-28 in 10 µm. A thickened central nodule is present on the primary side, positioned between the deflected proximal fissures.

Original Description

Author: R.M.Patrick 1944
Length Range: 33 µm
Width Range: 6 µm
Striae in 10 µm: 15-17

Original Description

Valva linearis vel lanceolata, 33 µ longa, 6µ lata, apicibus rotundatis: striis lineatis 15-17 per 10 µ, ad centrum valvae conspicue radiatis, ad margines valvae minus conspicuae radiatis; area axiali angusta; area centrali distincte rectangulare. In the general shape of the central area and the formation of the striae this species is quite similar to Navicula gracilis Ehr. and its varieties. However, it is typically smaller in size and the striae are more radiate in the center of the valve and radiate instead of convergent at the ends. Also the striae are finer (Fig. 6). Distribution-Brazil: Rio Grande do Sul, current water at roadside, near the Lagua dos Quadros, 385 H. Kleerekoper July: 1941 (A-25741). Type (A-25740), scrapings of stones in a rapid of the river Maquuine, an affluent of the Lagua dos Quadros 337 H. Kleerekoper June 1941 (A-25737).

Original Images

Cite This Page:
Manoylov, K., and Hamilton, P. (2010). Navicula symmetrica. In Diatoms of the United States. Retrieved May 24, 2018, from

Species: Navicula symmetrica

Contributor: Kalina Manoylov | Paul Hamilton

Reviewer: Sarah Spaulding


Patrick, R.M. (1944). Estudo Limnologico e Biologico das Lagoas da regiao Litoranea Sul- Riograndense II. Some New Diatoms from the Lagoa dos Quadros. Boletin de Museo Naciona, Nova serie, Botanica. 2:6 pp., 9 fig.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Navicula symmetrica CAS

NCBI Genbank Taxonomy

Navicula symmetrica NCBI

North American Diatom Ecological Database (NADED)


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

Navicula symmetrica

EMAP Response Plots

Navicula symmetrica

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.