(Ralfs ex Kützing) Williams and Round 1986 Category: Araphid
BASIONYM: Synedra pulchella Ralfs ex Kützing 1844
SYNONYM(S): Fragilaria pulchella (Ralfs ex Kützing) Lange-Bertalot | Synedra pulchella (Ralfs ex Kützing) Kützing
Contributor: Justin Kenneth Jones - June 2013
Length Range: 47-91 µm
Width Range: 4.3-7.6 µm
Striae in 10 µm: 14-16
Valves are elongate and linear to lanceolate, with capitate to rounded poles. Valves have a central area with a distinct fascia. The fascia may have ghost striae; these are indentations within the valve that do not open to the surface. The axial area is linear. The striae are parallel and clearly punctate. Each stria at the middle of the valve has about 5-6 areolae, striae at apices have 2-4 areolae. There is one rimoportula at each apex that is diagonal to the sternum, though this feature can be difficult to distinguish on light microscope on some specimens.
Larger specimens may be slightly sigmoid at the poles, and the shortest valves may have one pole slightly curved. Some valves can be slightly convex in girdle view. In some valves, the striae can diverge and become nonparallel. The sternum can be sigmoidal to irregular in shorter specimens. The variations in morphology may be indicative of multiple forms through Ctenophora pulchella life cycle, environmental conditions at the sampling site, and/or multiple varieties present within the sample.
Basionym: Synedra pulchella
Author: Ralfs ex Kützing 1844
Length Range: µm
Striae in 10 µm:
Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.
Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Williams, D.M. and Round, F.E. (1986). Revision of the genus Synedra Ehrenb. Diatom Research 1: 313-339.
Ctenophora pulchella was observed in brackish waters along coastal regions, as well as freshwater habitats with higher mineral content. The specimens imaged here are from a composite benthic sample from a heavily modified urban steam, Collins Channel from Orange County, California. Water pH at the site was 8.08, dissolved oxygen content was 5.73 mg/mL, conductivity was of 2946 µS/sm, and salinity was 1.54 ppt. Cells attach to macrophytes and other surfaces via a mucilage pad at one end and form tuft-shaped colonies.
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.