Entomoneis alata

(Ehrenb.) Ehrenb. 1845      Category: Asymmetrical biraphid
BASIONYM: Navicula alata Ehrenb. 1840
SYNONYM(S): Amphiprora alata (Ehrenb.) Kütz. 1844 

Encyonopsis subminuta


Entomoneis ornata

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - February 2012
Length Range: 48-129 µm
Width Range: 9.7-10.1 (valve, excluding keels); 14.9-18.8 (valve, including keels); 32-42 (girdle view) µm
Striae in 10 µm: 15-18


Valves in valve view at the valvar plane are linear-elliptic to linear lanceolate with slightly concave sides and apiculate apices. Highly arched bilobate keels dominate the view in girdle aspect. The keels are strongly torsioned so that only one lobe is in focus at one time. In complete frustules in girdle view, diagonally opposing lobes lie at approximately the same level of focus. Lobes are flattened in large specimens and more rounded in smaller specimens. Several girdle bands are present. The junction line between the valve and the keel, like the outer edge of the keel, is flattened in larger specimens and more rounded in smaller specimens. The junction line is marked by an irregular series of dark spots. In valve view these spots can be seen as thickened siliceous ribs that frame a series of prominent swellings along the junction line. The swellings are approximately equal in size. Striae on the valve face continue onto the keel. Areolae on the valve face are very fine and number 26-30 in 10 µm within a stria. Areolae on the keel are much more prominent and number 12-15 in 10 µm within a stria.

Original Description

Basionym: Navicula alata
Author: Ehrenb. 1840
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Bahls, L. (2012). Entomoneis alata. In Diatoms of the United States. Retrieved April 23, 2018, from http://westerndiatoms.colorado.edu/taxa/species/entomoneis_alata

Species: Entomoneis alata

Contributor: Loren Bahls

Reviewer: Rex Lowe


Ehrenberg, C.G. (1841). Characteristik von 274 neuen Arten von Infusorien. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlichen Preussischen Akademie der Wissenschaften zu Berlin, for 1840: 197-219.

Ehrenberg, C.G. (1845). Vorläufige zweite Mettheilung über die weitere Erkenntnifs der Beziehungen des kleinsten organischen Lebens zu den vulkanischen Massen der Erde. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin 1845:133-157.

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.

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

Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Entomoneis alata CAS

North American Diatom Ecological Database (NADED)

NADED ID: 31003

Autecology Discussion

Entomoneis alata occurs frequently in streams of the Northwestern Great Plains (Montana, North Dakota, South Dakota, Wyoming). In these waters the mean pH is 8.6 and the mean specific conductance is 4459 µS/cm. Sodium and sulfate are the dominant cation and anion, respectively. Common diatom associates of Entomoneis alata include Cymbella pusilla, Entomoneis paludosa, Biremis circumtexta, Navicula salinarum, Nitzschia reversa, Staurophora brantii, Nitzschia filiformis, Fallacia pygmaea, Pleurosigma delicatulum, and Navicula peregrina. There have been several reports of this species from across the United States in inland waters with elevated concentrations of electrolytes (Patrick & Reimer 1975).

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

Entomoneis alata

EMAP Response Plots

Entomoneis alata

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.