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Navicula pseudolanceolata

Lange-Bert. 1980      Category: Symmetrical biraphid

Navicula piercei


Navicula radiosa

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - December 2011
Length Range: 41-59 µm
Width Range: 9.0-11.1 µm
Striae in 10 µm: 9-11


Valves are lanceolate, with acutely pointed apices in smaller specimens and weakly protracted, narrowly rounded apices in larger specimens. The axial area is narrow, widening into a small rhombic central area. The raphe is weakly lateral and essentially straight, with relatively distant and only slightly expanded proximal ends. Striae are irregularly shortened and more widely spaced about the central area, strongly radiate and mostly straight, becoming parallel, but not convergent at the valve apices. Lineolae are coarse and number 24 in 10 µm.

Original Description

Author: Lange-Bert. 1980
Length Range: 30-50 µm
Width Range: 7-9.5 µm
Striae in 10 µm: 9.5-11

Original Description

Valves lanceolate to rhombic-lanceolate, ends gradually narrowed, wedge-shaped, length 30-50 microns, breadth 7-9.5 microns. Raphe weakly lateral, axial area narrow, central area small to moderately larger, slightly rhombic to transversely widened. Striae strongly radiate throughout or parallel at the ends, 9.5-11/10 microns; lineolae appear coarse, c. 24/10 microns.

Original Images

Cite This Page:
Bahls, L. (2011). Navicula pseudolanceolata. In Diatoms of the United States. Retrieved May 26, 2018, from

Species: Navicula pseudolanceolata

Contributor: Loren Bahls

Reviewer: Marina Potapova


Lange-Bertalot, H. (1980). Zur taxonomischen Revision einiger ökologisch wichtiger “Navicula lineolatae” Cleve. Die Formenkreise um Naviculae lanceolata, N. viridula, N. cari. Cryptogamie, Algologie 1(1):29-50.

Lange-Bertalot, H. (2001). Navicula sensu stricto, 10 genera separated from Navicula sensu lato, Frustulia. Diatoms of Europe 2: 1-526.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Navicula pseudolanceolata CAS

North American Diatom Ecological Database (NADED)

NADED ID: 46153

Autecology Discussion

There are 82 records of Navicula pseudolanceolata in the Montana Diatom Collection, from lakes and streams in mountain regions of the Northwest United States. The species is rarely found in abundance. Specimens pictured here are from Lower Branham Lake in the Tobacco Root Mountains of southwest Montana. At the time of sampling this lake had a pH of 8.74 and specific conductance of 64 µS/cm. Lange-Bertalot (2001) reports N. pseudolanceolata from low conductivity or weakly humic acid and oligotrophic lakes in Europe.


Lower Branham Lake, Madison County, Montana: home of Navicula pseudolanceolata.

Credit/Source: Loren Bahls

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 pseudolanceolata

EMAP Response Plots

Navicula pseudolanceolata

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.