Contributor: Marina Potapova - February 2011
Length Range: 23-57 µm
Width Range: 8-13 µm
Striae in 10 µm: 8-11 in the valve center
Valves are moderately dorsi-ventral, with rounded or slightly protracted, blunt apices. The dorsal margin is strongly arched, whereas the ventral margin is flat or slightly convex. The central area is small, elliptical. Two (rarely one or three) stigmata are present at the end of the middle striae. The proximal raphe ends have central pores that curve to the ventral margin. The raphe is lateral, becoming filiform near the distal end. Striae are radiate. The areolae are apically elongated, they number 17-20 in 10 μm.
Author: Krammer 2002
Length Range: µm
Striae in 10 µm:
Cymbella subturgidula nov. spec. [Figs 44: 19-21]
Type locality: Korea, Ulchin County, Kyungsang Pukdo, Kwangchun River, slide 1046c IOK.
Valves distinctly dorsiventral, broadly lanceolate, dorsal margin strongly arched, ventral margin moderately convex. Ends not to barely protracted and bluntly rounded. Length 36-37 μm, breadth 10-11 μm, maximal length/breadth ratio 3.7. Axial area narrow, linear or slightly curved. Central area very small, roundish. Raphe somewhat ventrally displaced, distinctly lateral, becoming filiform near the distal and slightly reverse-lateral towards the proximal ends. Proximal raphe ends have distinct central pores, terminal fissures dorsally deflected. Striae radiate in the middle portion, becoming more radiate near the ends, distinctly punctate-lineolate. Two isolated stigmata just at the ends from the middle striae on the ventral side or very slightly separated from these. Striae in the middle portion 10-11/10 μm (dorsal and ventral), becoming up to 15/10 μm towards the ends, puncta about 24 /10 μm.
Differential diagnosis: Distinguished from the other taxa in particular from C. metzeltinii by more finely punctate striae, the smaller central area, the commonly two stigmata and the larger length/breadth ratio.
Krammer, K. (2002). The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584.
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.