Cymbella affinis

Kütz. 1844      Category: Asymmetrical biraphid

REPORTED AS: Cymbella excisa (Krammer 2002) 

Cymbella affiniformis


Cymbella alpestris

LM scalebar = 10 µm = 80 pixels.


Contributor: Marina Potapova - August 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.

Original Description

Author: Kütz. 1844
Length Range: µm
Striae in 10 µm:

Original Description

  1. CYMBELLA AFFINIS. Taf. 6. Fig. XV. (420/1). C. minuta, utrinque obtusiuscula, dorso elatiori, ostiolis terminalibus majoribus hyalinis, latere primario majori elliptico-oblongo; striis transversalibus distinctis in 1/100 ”’ 19. Cocconema Fusidium Ehrenb.? Inf. 1838. p. 226. — Amer. Taf. II. 1. 35. 11. 21.? — Cymbella ventricosa De Brébisson! (ex specim.) Falaise: De Brébisson! (Herb. Binder.) Schleswig: Herb. Binder! — Central-Amerika? — Fossil in schwedischem Bergmehl. — Länge 1/85”’.

Original Images

Cite This Page:
Potapova, M. (2011). Cymbella affinis. In Diatoms of the United States. Retrieved April 21, 2018, from

Species: Cymbella affinis

Contributor: Marina Potapova

Reviewer: Pat Kociolek


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.) Süsswasserflora 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.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Cymbella affinis CAS

NCBI Genbank Taxonomy

Cymbella affinis NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 23073

Autecology Discussion

EMAP Assessment

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.

EMAP Distribution

Cymbella affinis

EMAP Response Plots

Cymbella affinis

EMAP citations

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.