Pseudofallacia tenera

(Hust.) Liu, Kociolek and Wang 2012      Category: Symmetrical biraphid
BASIONYM: Navicula tenera Hust. in Schmidt et al. 1936
SYNONYM(S): Fallacia tenera (Hust.) D.G.Mann in Round et al. 

Pseudofallacia monoculata


Pseudostaurosira americana

LM scalebar = 10 µm = 80 pixels.


Contributor: Pat Kociolek - March 2011
Length Range: 6-11 µm
Width Range: 3.5-5.0 µm
Striae in 10 µm: 13-16


Larger valves are linear-elliptic, while smaller valves are broadly rounded. The axial area is straight, narrow and contains a filiform, straight raphe. The striae are radiate to nearly parallel and composed of distinct areolae. A small lyre-shaped hyaline area is present on either side of the axial area.

Original Description

Basionym: Navicula tenera
Author: Hust. in Schmidt et al. 1936
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Kociolek, P. (2011). Pseudofallacia tenera. In Diatoms of the United States. Retrieved April 23, 2018, from

Species: Pseudofallacia tenera

Contributor: Pat Kociolek

Reviewer: Rex Lowe


Krammer, K. and Lange-Bertalot, H. (1986). Bacillariophyceae. 1. Teil: Naviculaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Süsswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 pp.

Liu, Y., Kociolek, J.P., Fan, Y. and Wang, Q. (2012). Pseudofallacia gen. nov., a new freshwater diatom (Bacillariophyceae) genus based on Navicula occulta Krasske. Phycologia 51(6): 620–626.

Round, F.E., Crawford, R.M. and Mann, D.G. (1990). The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.

Sabbe, K., Vyverman, W. and Muylaert, K. (1999). New and little-known Fallacia species (Bacillariophyta) from brackish and marine intertidal sandy sediments in Northwest Europe and North America. Phycologia 38(1): 8-22.

Stancheva, R. and Manoylov, K.M. (2018). Fallacia californica sp. nov. (Bacillariophyta), a new freshwater diatom species from streams in California, USA. Phytotaxa 345 (2): 104–118. 10.11646/phytotaxa.345.2.2

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Pseudofallacia tenera CAS

North American Diatom Ecological Database (NADED)

NADED ID: 115008

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

Pseudofallacia tenera

EMAP Response Plots

Pseudofallacia tenera

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.


- Transfer to Pseudofallacia

The genus Pseudofallacia was established by Liu et al. (2012) to accommodate small species that had previously been included in Fallacia and Navicula. As of this date, the website reflected this change for P. tenera. - S. Spaulding