(Ehrenberg) Williams and Round 1987 Category: Araphid
BASIONYM: Biblarium leptostauron Ehrenberg 1854
SYNONYM(S): Fragilaria leptostauron (Ehrenberg) Hustedt
Contributor: Eduardo Morales - October 2010
Length Range: 7-33 µm
Width Range: 7-19 µm
Striae in 10 µm: 5-11
Valves are cruciform, 7-19 µm wide and 7-33 µm long. Valves with rounded ends. The central area is broad. The valve face is flat, or slightly undulate due to raised costae. The valve face/mantle junction forms a sharp angle. The abvalvar edge of the mantle is parallel to the valve face/mantle junction. In girdle view, frustules are rectangular. Cells form ribbon-like colonies, joined by linking spines. A cell within a colony is attached to the substratum by a mucilage pad, or cells may be planktonic. The axial area is linear to lanceolate. Striae are distinct, composed of lineolae. Lineolae are greatest in length midway between the sternum and valve mantle, 5-11 in 10 µm. Lineolae bear finely branched volae and may possess siliceous bridges between lineolae. Striae are parallel in the central area, becoming radiate near the valve ends. Striae extend onto the valve mantle. Costae are not as broad as the striae. Spines are flat, spatulate toward their ends and solid. Spines are present along the valve face edge, except at the apices, and are located on the costae between striae. Well-developed, ocellulimbus type, apical pore ﬁelds with round poroids are present. Pore fields are located at the junction between the valve face/mantle. Rimoportulae are absent. Copulae, or girdle bands, are closed and do not bear perforations. Valvocopulae are wider than other girdle elements and bear fimbriae (finger-like projections).
Basionym: Biblarium leptostauron
Author: Ehrenberg 1854
Length Range: µm
Striae in 10 µm:
Williams, D.M. and Round, F.E. (1987). Revision of the genus Fragilaria. Diatom Research 2: 267-288.
Cells are attached by mucilage pads to substrates and joined in colonies by linking spines.
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.