Cymbella affinis

Kützing 1844      Category: Asymmetrical biraphid
BASIONYM: Cymbella affinis Kützing 1844

REPORTED AS: Cymbella excisa (Krammer 2002) 

Cymatopleura solea

 

Cymbella amplificata
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LM scalebar = 10 µm = 40 pixels.

Observations

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

Description

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

Basionym: Cymbella affinis
Author: Kützing 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 July 25, 2014, from http://westerndiatoms.colorado.edu/taxa/species/cymbella_affinis

Species: Cymbella affinis

Contributor: Marina Potapova

Reviewer: Pat Kociolek

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Image Credit: Marina Potapova

  1. Valves strongly dorsi-ventral
  2. Valves 6.9-9.0 μm wide
  3. Central area not distinct
  4. One stigma
  5. Areolae 25-30 in 10 μm

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 central area is very small or not distinct. One stigma is present at the end of the middle striae. The areolae number 25-30 in 10 μm.

Compare

Cymbella affinis differs from C. excisiformis by wider valves and less distinct areolae.

Cymbella excisiformis

Citations

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.

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

Habits

Size Range

101-1000 µm3 (ie Amphora veneta)
1001-10,000 µm3 (ie Diatoma vulgaris)

Motility

slightly motile (e.g. Cocconeis)

Attachment

vertical (e.g. stalks)

Habitat

benthic

Colony

colonies common

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

Distribution

The distribution map represents the relative abundance of this Cymbella affinis in the western EMAP study. Relative abundance is a measure of the proportion of cells of this species based on a "fixed count" of 300 total diatom cells counted and identified. Each of the western EMAP sample sites is shown, either with a black dot for sites where Cymbella affinis was not recorded, or with a red circle indicating the relative abundance of Cymbella affinis.

Note that the size of the proportional symbols varies between species to help show both abundant and rare species.

Scale for the map to the left

EMAP Response Plots

Cymbella affinis

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Cymbella affinis from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.

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.