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Diatoms of the United States is now known as Diatoms of North America.
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Geissleria ignota

(Krasske) Lange-Bert. and Metzeltin 1996      Category: Symmetrical biraphid
BASIONYM: Navicula ignota Krasske 1932

Geissleria decussis


Geissleria kriegeri

LM scalebar = 10 µm = 80 pixels.


Contributor: Rex Lowe - December 2011
Length Range: 16-18 µm
Width Range: 3.0-3.2 µm
Striae in 10 µm: 15-16


Valves are triundulate with rostrate to subcapitate ends. The central area is expanded laterally with 2-4 shortened striae at the valve margin. The striae are radiate near the center of the valve becoming parallel near the ends. Two to three rows of annulae are at each apex of the valve.

Original Description

Basionym: Navicula ignota
Author: Krasske 1932
Length Range: 17-25 µm
Width Range: 4.5-5 µm
Striae in 10 µm: 12-14

Original Description

Linear, dreiwellig, Enden gerundet. Lang 17-25µ, breit 4,5-5µ. 12-14 Streifen in 10 µ, gebogen, die konvexe Seite den Enden zugewandt, die mittelsten stark verkürzt, so daB sich die schmale, lineare Längsarea in der Mitte fast bis zum Rande erweitert. Die mittleren Streifen konvergierend , gegen die Enden senkrecht zur Raphe.

Original Images

Cite This Page:
Lowe, R. (2011). Geissleria ignota. In Diatoms of the United States. Retrieved May 24, 2018, from

Species: Geissleria ignota

Contributor: Rex Lowe

Reviewer: Sarah Spaulding


Krasske, G. (1932). Beiträge zur Kenntnis der Diatomeenflora der Alpen. Nova Hedwigia 72(3): 92-135.

Lange-Bertalot, H. and Metzeltin, D. (1996). Indicators of oligotrophy - 800 taxa representative of three ecologically distinct lake types, Carbonate buffered - Oligodystrophic - Weakly buffered soft water. Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 2. Ecology, Diversity, Taxonomy. Koeltz Scientific Books. Königstein, Germany, 2:390 pp.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Geissleria ignota CAS

North American Diatom Ecological Database (NADED)

NADED ID: 210005

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

Geissleria ignota

EMAP Response Plots

Geissleria ignota

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.