(Ehrenberg) Kützing 1844 Category: Epithemioid
BASIONYM: Navicula turgida Ehrenberg 1832
Contributor: Rex Lowe - December 2010
Length Range: 45-166 µm
Width Range: 13.5-17 µm
Striae in 10 µm: 8-10
Valves are dorsiventral and are 45-166 μm long and 13.5 to 17 μm wide. Valves taper toward rounded to rostrate to slightly capitate ends. Striae are 8-10 in 10 μm and costae are 4-5 in 10 μm. There are 2-3 striae between costae. The dorsal margin is strongly convex and the ventral margin is slightly concave. The raphe canal lies against the ventral margin at distal ends of the valve and arches toward the dorsal margin in the valve center. The central arch of the canal is approximately 7-8 μm above the ventral margin reaching almost half the distance to the dorsal margin.
Basionym: Navicula turgida
Author: Ehrenberg 1832
Length Range: 45-225 µm
Striae in 10 µm:
DeYoe, H.R., Lowe, R.L. and Marks, J.C. . (1992). Effects of nitrogen and phosphorus on the endosymbiont load of Rhopalodia gibba and Epithemia turgida (Bacillariophyceae). Journal of Phycology 28: 723–873. 10.1111/j.0022-3646.1992.00773.x
Krammer, K. and Lange-Bertalot, H. (1988). Bacillariophyceae. 2. Teil: Bacillariaceae, Epithemiaceae, Surirellaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/2. Gustav Fisher Verlag, Jena.
Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.
Sims, P.A. (1983). A taxonomic study of the genus Epithemia with special reference to the type species E. turgida (Ehrenb.) Kütz. Bacillaria 6: 211-235.
Similar to other species of Epithemia, E. turgida contain nitrogen-fixing endosymbiotic cyanobacteria which enable this taxon to become abundant in microhabitats with a low N/P ratio. It is frequently very abundant as an epiphyte on Cladophora and other coarse filamentous algae in western rivers.
Epithemia turgida (larger cells) and E. sorex (smaller cells) epiphytic on Cladophora from the Eel River, California.
Credit/Source: R. Lowe
Live Epithemia turgida showing endosymbiotic cyanobacteria.
Credit/Source: R. Lowe
Sampling for 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). Streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming). Over 1200 sites on 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.
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.