Kützing 1844 Category: Asymmetrical biraphid
BASIONYM: Cymbella affinis Kützing 1844
REPORTED AS: Cymbella excisa (Krammer 2002)
Contributor: Marina Potapova - September 2011
Length Range: 19-36 µm
Width Range: 6.9-9.0 µm
Striae in 10 µm: 9-12 in the center valve, 13-14 at the ends
Valves are strongly dorsi-ventral, with subrostrate to rostrate apices. The dorsal margin is strongly arched, whereas the ventral margin is slightly convex or flat, often excised. The axial area is narrow, linear. The central area is very small or not distinct. One stigma is present at the end of the middle striae. The proximal raphe ends have central pores that curve to the ventral side. The raphe is lateral, becoming filiform near the distal end. Striae are slightly radiate. The areolae number 25-30 in 10 μm.
Note that this concept of Cymbella affinis is based on Kützing's type material examined by Reimer (see image below) and by Tuji (2007) and is different from the concept of Krammer (2002). Krammer examined material labeled C. affinis in W. Smith's collection within the Van Heurck collection, Antwerp, which contains C. tumidula Grunow. Therefore, Krammer claimed that these two species are synonymous and the name C. affinis has to be applied to diatom so far known as C. tumidula. Reimer's (below) and Tuji (2007) photographs of the type material of C. affinis, show, however, that Krammer's decision is incorrect, while C. affinis and C. excisa are conspecific. Kützing applied the name C. affinis to specimens without excision and C. excisa to specimens with excised ventral margin.
Basionym: Cymbella affinis
Author: Kützing 1844
Length Range: µm
Striae in 10 µm:
Krammer, K. (2002). The genus Cymbella. Diatoms of Europe. Diatoms of the European Inland Waters and Comparable Habitats 3: 1-584.
Krammer, K. and Lange-Bertalot, H. (1986). Bacillariophyceae. 1. Teil: Naviculaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 pp.
Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.
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.
Tuji, A. (2007). Type examination and typification of Cymbella affinis Kutz., C. turgidula Grunow and C. uenoi Skvotsov. Diatom 23: 49-54.
Sampling for 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). Streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming). Over 1200 sites on 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.