Ehrenberg 1844 Category: Symmetrical biraphid
BASIONYM: Navicula rhynchocephala Kützing 1844
Contributor: Pat Kociolek - March 2011
Length Range: 48-53 µm
Width Range: 9-10 µm
Striae in 10 µm: 8-9 at the center, 11-12 towards the apices
Valves are lanceolate with elongate-protracted, rounded apices. The axial area is narrow, straight, widening to form an irregularly-rounded to elliptical central area. The central area is formed by shortened striae that are also more widely spaced than elsewhere on the valve. The raphe is lateral, slightly arched, with dilated proximal raphe ends. Striae are distinctly lineolate, radiate around the center, becoming parallel, then convergent at the ends.
Taxonomic note: We present N. rhynchocephala following Lange-Bertalot (2001). The specimen illustrated as N. rhynchocephala in Patrick & Reimer (1966) corresponds to our treatment of N. rhynchotella. The type material of N. rhynchocephala, however, has not been investigated and further work may clarify the original type as designated.
Basionym: Navicula rhynchocephala
Author: Kützing 1844
Length Range: µm
Striae in 10 µm:
Lange-Bertalot, H. (2001). Navicula sensu stricto, 10 genera separated from Navicula sensu lato, Frustulia. Diatoms of Europe 2: 1-526.
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.