(Ehrenberg) Cleve 1894 Category: Asymmetrical biraphid
BASIONYM: Cocconema asperum Ehrenberg 1840
Contributor: Loren Bahls - June 2016
Length Range: 112-221 µm
Width Range: 25.2-38.5 µm
Striae in 10 µm: 7-9 at the valve center, 10-11 near the apices
Valves are dorsiventral, with rounded apices. The dorsal margin is distinctly arched and the ventral margin is slightly concave, with a gibbous middle portion. The central area is only slightly wider than the axial area. The central area is asymmetric, rounded on the dorsal side and nearly flat on the ventral side. The ventral side of the central area is bordered by irregularly spaced areolae. Stigma or stigmata are absent. The raphe is narrow near the proximal ends and is deflected slightly toward the ventral margin. The proximal raphe ends are expanded. Terminal raphe fissures are sickle-shaped and deflected dorsally. Striae are radiate throughout. Areolae are distinct and number 9-11 in 10 µm.
Basionym: Cocconema asperum
Author: Ehrenberg 1840
Length Range: µm
Striae in 10 µm:
Cleve, P.T. (1894). Synopsis of the Naviculoid Diatoms, Part I. Kongliga Svenska-Vetenskaps Akademiens Handlingar 26(2):1-194, 5 pls.
Ehrenberg, C.G. (1840). Characteristik von 274 neuen Arten von Infusorien. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin 1840: 197-219.
Ehrenberg, C.G. (1854). Mikrogeologie. Einundvierzig Tafeln mit über viertausend grossentheils colorirten Figuren, Gezeichnet vom Verfasser. Voss, Leipzig., Pl. 5, II, fig. 23 (iconotype).
Krammer, K. (2002). The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584.
Patrick, R.M. and Reimer, C.W. (1975). The Diatoms of the United States, exclusive of Alaska and Hawaii, V. 2. Monographs of the Academy of Natural Sciences of Philadelphia 13.
Peragallo, H. (1889). Liste des diatomées francaises. In: Les diatomées II (J. Pelletan, ed.), pp. 213-297.
Cymbella aspera is widely distributed in alkaline waters with low nutrients and low to moderate electrical conductance, but seldom found in large numbers. It is often encountered in lakes, ponds, fens, springs and creeks in the northern Rocky Mountains.
Atlantic Pond, Glacier National Park, Montana: home of Cymbella aspera.
Credit/Source: Loren Bahls
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.