(Krasske) Hustedt 1957 Category: Symmetrical biraphid
BASIONYM: Navicula creuzburgensis Krasske 1927
Contributor: Carrie Graeff - February 2011
Length Range: 26-38 µm
Width Range: 6.0-8.0 µm
Striae in 10 µm: 24-26 at the center, 28-30 at the ends
Valves with slightly rostrate, rounded apices, 26.0 - 38.0 µm in length by 6.0 - 8.0 µm in breadth. Valve mantle of moderate depth. The two raphe branches are arched along their entire length, resulting in asymmetrical valve face ornamentation. The distal raphe ends begin more or less centered along the longitudinal axis, and the raphe curves unilaterally toward the dorsal margin as it approaches the central area. The external proximal raphe ends are deflected in the same direction as the curve of the raphe branches. Enlarged poroids occur near the external distal raphe ends, positioned within a transverse depression. Striae are composed of rows of round, although commonly elongate, areolae. Areolae are internally occluded. The valvocopula is closed, and includes a row of projections on the internal side and a rough external notch near the center of the band. The notch is of varying size and shape and exposes a series of alternating poroids and small protuberances. In addition to the valvocopula, four open copulae are present, each with two rows of poroids.
Basionym: Navicula creuzburgensis
Author: Krasske 1927
Length Range: 30.0-45.0 µm
Width Range: 6.0-8.0 µm
Striae in 10 µm: 18
Cholnoky, B. (1959). Neue und seltene Diatomeen aus Afrika. IV. Diatomeen aus der Kaap-Provinz. Österreichische Botanische Zeitschrift, Vol: 106, Issue: 1/2, 1-69 .
Hustedt, F. (1957). Die Diatomeenflora des Flußsystems der Weser im Gebiet der Hansestadt Bremen. Abhandlungen des Naturwissenschaftlichen Verein zu Bremen 34(3):181-440.
Krasske, G. (1927). Diatomeen deutscher Solquellen und Gradierwerke. Archiv für Hydrobiologie 18:252-272, pl. 10.
Patrick, R.M. (1959). New species and nomenclatural changes in the genus Navicula (Bacillariophyceae). Proceedings of the Academy of Natural Sciences of Philadelphia, 111, 91-108.
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.