Contributor: Pat Kociolek -
Length Range: 12-20 µm
Width Range: 4 µm
Striae in 10 µm: 22-28
Valves are lanceolate to elliptical-lanceolate, with protracted apices. The raphe is distinct, positioned off center and contained within a canal. Transapical costae are distinct. The striae are punctate. Included in this concept is D. tenuis var. crassula (Naeg. ex Kützing) W. & G.S. West, which appears to represent valves at the lower size range of D. tenuis.
Specimens we have encountered occupy a narrow size range. Patrick and Reimer (1966) give the size range as 6-60 µm long, 3-7 µm broad. Found in alkaline waters across the United States.
Basionym: Denticula tenuis
Author: Kützing 1844
Length Range: µm
Striae in 10 µm:
Hamsher, S.E., Graeff, C.L., Stepanek, J.G. and Kociolek, J.P. (2014). Frustular morphology and polyphyly in freshwater Denticula (Bacillariophyceae) species, and the description of Tetralunata gen. nov. (Epithemiaceae, Rhopalodiales). Plant Ecology and Evolution 147 (3): 346–365. 10.5091/plecevo.2014.990
Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.
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.
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.