(Ehrenberg) Compère 1982 Category: Centric
BASIONYM: Biddulphia laevis Ehrenberg 1843
SYNONYM(S): Cerataulus laevis (Ehrenberg) Ralfs in Pritchard 1861
Contributor: Pat Kociolek - March 2011
Diameter: 65–120 µm
Rows of areolae in 10 µm: 12-13 at the margin of valve
Valves circular to elliptical. The valve face is slightly hemispherical. Two ocelli are present, positioned opposite one another, composed of fine rows of porelli. The ocelli are not the same size; one is much larger than the other. Two-three rimoportulae are present, each with a small, hyaline area surrounding the opening. Striae are radiate and number 12-13 in 10 μm at margin of valve face. Areolae are in short radial rows at the valve margin, irregularly arranged in central part of valve. Areola density is 12-18 in 10 μm. Spinules are present across valve face and at the margin.
Living cells are joined in zig-zag chains, with cells attached to one another by mucilage at the opposing cell’s ocelli.
Kociolek et al. (1983) reported this species from inland habitats in Ohio, and a related species was recently described from India (Karthick and Kociolek 2011). Images from Krammer and Lange-Bertalot (1991) are more similar to those depicted here (from California) than the images from Kociolek et al. More research is needed to clarify the relationships of these populations.
Basionym: Biddulphia laevis
Author: Ehrenberg 1843
Rows of areolae in 10 µm:
Krammer, K. and Lange-Bertalot, H. (1991). Bacillariophyceae. 3. Teil: Centrales, Fragilariaceae, Eunotiaceae. In Ettl, H., Gerloff, J., Heynig, H. & Mollenhauer, D. (Eds.). Süsswasserflora von Mitteleuropa. 2(3): 1-576. Gustav Fisher Verlag, Stuttgart, Germany.
A small mother cell (left) and auxospore of Pleurosira laevis. The auxospore is 121 µm in length. Cells are from the Caloosahatchee River, Fort Myers, Florida (Lat: 26.6582, Long: -81.8532).
Credit/Source: Emily Nodine
A group of cells of Pleurosira laevis in girdle view, along with an auxospore in valve view. The auxospore is 129 µm in length. Cells are from the Caloosahatchee River, Fort Myers, Florida (Lat: 26.6582, Long: -81.8532).
Credit/Source: Emily Nodine
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.