Amphora ovalis

(Kütz.) Kütz. 1844      Category: Asymmetrical biraphid
BASIONYM: Frustulia ovalis Kütz. 1833
SYNONYM(S): Navicula amphora Ehrenb. 

Amphora minutissima


Amphora pediculus

LM scalebar = 10 µm = 40 pixels.


Contributor: Joshua Stepanek | Pat Kociolek - January 2011
Length Range: 32-95 µm
Width Range: 8-17 µm
Striae in 10 µm: 10-12


Valves are semi-elliptic with a smoothly arched dorsal margin and slightly concave ventral margin. Valve ends are rounded. The axial area is narrow. An uninterrupted raphe ledge (a thin, elevated T-shaped structure that extends laterally to the raphe) is present. The raphe ledge is visible, extending the length of the cell and covering the dorsal and ventral striae near the axial area. The raphe is linear and arched dorsally. Proximal and distal raphe ends are deflected dorsally. Dorsal striae are interrupted transapically by intercostal ribs. The dorsal striae are slightly radiate centrally, becoming more radiate toward the apices. Ventral striae consist of an uninterrupted row of single areolae, slightly radiate centrally becoming convergent at the apices. A dorsal fascia is absent. A ventral fascia is present, extending to the ventral margin.

Original Description

Basionym: Frustulia ovalis
Author: Kütz. 1833
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Stepanek, J., and Kociolek, P. (2011). Amphora ovalis. In Diatoms of the United States. Retrieved April 26, 2018, from

Species: Amphora ovalis

Contributor: Joshua Stepanek | Pat Kociolek

Reviewer: Sarah Spaulding


Krammer, K. (1980). Morphologic and taxonomic investigations of some freshwater species of the diatom genus Amphora Ehr. Bacillaria 3:197-225.

Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.

Lee, K. and Round, F.E. (1987). Studies on freshwater Amphora species. I. Amphora ovalis. Diatom Research 2 (2): 193-203. 10.1080/0269249X.1987.9704997

Schoeman, F.R. and Archibald, R.E.M. (1986). Observations on Amphora species (Bacillariophyceae) in the British Museum (Natural History). V. Some species from the subgenus Amphora. South African Journal of Botany. 53: 425-437.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Amphora ovalis CAS

NCBI Genbank Taxonomy

Amphora ovalis NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 7001

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

Amphora ovalis

EMAP Response Plots

Amphora ovalis

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.