Kützing 1844 Category: Symmetrical biraphid
BASIONYM: Navicula rostellata Kützing 1844
SYNONYM(S): Navicula viridula var. rostellata (Kützing) Cleve
Valves are linear to linear-lanceolate with slightly convex (more typically) to straight margins and subrostrate apices. The axial area is narrow and straight. The central area is elliptic and slightly asymmetric. The raphe is straight, with external proximal raphe ends that are slightly dilated and bent toward the primary side of the valve. The central nodule is asymmetrically expanded on the internal valve surface to the primary side. Terminal raphe fissures are hooked to the secondary valve side. Striae are bent and radiate around the center. The striae are more distant from one another near the center of the valve, 12-14 in 10 µm. The striae become parallel, then convergent at the apices. The areolae are usually visible under LM and number around 30 in 10 μm.
Note that the original material of Navicula rostellata has not been investigated. As Patrick (Patrick & Reimer 1966) pointed out, the identity of this taxon is not clear as the original illustration shows a linear valve outline and long, narrow apices. Patrick and Reimer (1966) illustrated a specimen from Bengal with linear valve outline and low striae density (9-10 striae in 10 µm) as N. viridula var. rostellata. The concept we present in this page follows Lange-Bertalot (2001).
Basionym: Navicula rostellata
Author: Kützing 1844
Length Range: 25-38 µm
Striae in 10 µm:
N. minuta, striata, oblonga, lateribus parallelis, apicibus rostratis elongates acutis. Long. 1/90-1/60’’’.
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.