Cocconeis pseudothumensis

E.Reichardt 1982      Category: Monoraphid

Cocconeis placentula


Cocconeis rugosa

LM scalebar = 10 µm = 80 pixels.


Contributor: Rex Lowe - February 2015
Length Range: 9-15 µm
Width Range: 6.9-10.6 µm
Striae in 10 µm: rapheless: 10-14, raphe: 25-27 at margin, 38-40 near axial area


Valves are broadly elliptical. The raphe valve has a narrow axial area, although the striae near the axial area may not be visible in LM. The striae are fine and radiate. The striae on the raphe valve number 25 to 27 in 10 µm near the valve margin, and near 40 in µm near the axial area. The rapheless valve has a broad, lanceolate axial area that covers 1/3 to 1/2 the width of the valve. The striae are coarse, square to elliptical, and radiate. The number of areolae ranges from 3 to 5.

Original Description

Author: E.Reichardt 1982
Length Range: 11.5-13.5 µm
Width Range: 8.5-9.5 µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Lowe, R. (2015). Cocconeis pseudothumensis. In Diatoms of the United States. Retrieved April 23, 2018, from

Species: Cocconeis pseudothumensis

Contributor: Rex Lowe

Reviewer: Marina Potapova


Krammer, K. and Lange-Bertalot, H. (2004). Bacillariophyceae 4. Teil: Achnanthaceae, Kritische Erganzungen zu Navicula (Lineolatae), Gomphonema Gesamtliteraturverzeichnis Teil 1-4 [second revised edition]. In: H. Ettl et al., Suesswasserflora von Mitteleuropa. Spektrum Akademischer Verlad Heidelberg, 468 pp.

Reichardt, E. (1982). Die Diatomeenflora der “Steinernen Rinnen” in Mittelfranken. Berichte der Bayerischen Botanischen Gesellschaft (zur Erforschung der heimischen Flora) 53: 97-112.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Cocconeis pseudothumensis CAS

North American Diatom Ecological Database (NADED)

NADED ID: 16017

Autecology Discussion

This species has been reported from northern Europe, Canada and New England, USA. It is probably most common in lotic ecosystems.

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

Cocconeis pseudothumensis

EMAP Response Plots

Cocconeis pseudothumensis

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.