Cocconeis pediculus

Ehrenb. 1838      Category: Monoraphid

Cocconeis klamathensis


Cocconeis placentula

LM scalebar = 10 µm = 40 pixels.


Contributor: Catharina Grubaugh | Marina Potapova - June 2012
Length Range: 17-42 µm
Width Range: 14-23 µm
Striae in 10 µm: 16-22 in the raphe valve center, 16-21 in the rapheless valve center


Valves are subcircular to broadly elliptic-lanceolate with curved to slightly pointed apices. The frustule is bent into a saddle-shape, with the raphe valve face transapically concave. The axial area of the raphe valve is narrow with a small, irregular central area. The terminal raphe fissures are straight. The proximal raphe ends are straight, and the raphe extends into the central area. The rapheless valve is transapically convex with a narrow sternum running down the middle. Striae are uniseriate on both valves. In the middle of the valves, striae are parallel, and striae closer to the apices are progressively more radiate and curved. On the raphe valve, the striae end before reaching the valve margin, forming an unornamented ring, which is wider on the sides of the valve than at the apices. Striae continue to the valve margin on the rapheless valve. Areolae are small and punctate on the raphe valve, and there are 17-24 areolae in 10 μm. On the rapheless valve, the areolae are narrow and transapically elongate. There are 6-11 areolae in 10 μm on the rapheless valve. The valve length-to-width ratio ranges from 1.1 to 1.6. The valvocopula may separate from the valve in prepared samples and appears as a ring with small projections that extend into the cell.

Jahn et al. (2009) examined the original material of Ehrenberg for Cocconeis pediculus and Cocconeis placentula var. placentula, including emended species descriptions and designation of epitypes.

Original Description

Author: Ehrenb. 1838
Length Range: µm
Striae in 10 µm:

Original Description

C. testula ovata, dorso valde convexo, semiglobosa, extus et intus laevis.

Original Images

Cite This Page:
Grubaugh, C., and Potapova, M. (2012). Cocconeis pediculus . In Diatoms of the United States. Retrieved April 22, 2018, from

Species: Cocconeis pediculus

Contributor: Catharina Grubaugh | Marina Potapova

Reviewer: Kalina Manoylov


Brown, B.J. and Olive, J.H. (1995). Diatom communities in the Cuyahoga River (USA): Changes in species composition between 1974 and 1992 following renovations in wastewater management. Ohio Journal of Science 95(3): 254-260.

Ehrenberg, C.G. (1838). Die Infusionsthierchen als vollkommene Organismen. Ein Blick in das tiefere organische Leben de Natur. erlag von Leopold Voss, Leipzig. pp. 1-xvii, 1-548, pls. 1-64.

Hardwick, G.G., Blinn, D.W. and Usher, H.D. (1992). Epiphytic diatoms on Cladophora glomerata in the Colorado River, Arizona: Longitudinal and vertical distribution in a regulated river. The Southwestern Naturalist 37(2):148-156.

Jahn, R., Kusber, W.H. and Romero, O.E. (2009). Cocconeis pediculus Ehrenberg and C. placentula Ehrenberg var. placentula (Bacillariophyta): Typification and taxonomy. Fottea 9(2): 275–288.

Lange, C.B. and Tiffany, M.A. (2002). The diatom flora of the Salton Sea, California. Hydrobiologia 473: (1-3) 179-201. 10.1023/A:1016550205461

Malkin, S.Y., Sorichetti, R.J., Wiklund, J.A. and Hecky, R.E. (2009). Seasonal abundance, community composition, and silica content of diatoms epiphytic on Cladophora glomerata. Journal of Great Lakes Research 35(2): 199-205.

Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Cocconeis pediculus CAS

NCBI Genbank Taxonomy

Cocconeis pediculus NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 16011

Autecology Discussion

Cocconeis pediculus was found in an epilithon sample from the Bronx River, southeastern New York state (early April); in plankton, epiphyton, epipelon, and epilithic samples from Lake Okoboji, Dickinson County, Iowa (late May); and in high abundance in a epilithon sample from Grove Lake, Antelope County, Nebraska (late May). The Reimer Collection at Iowa Lakeside Lab contains C. pediculus specimens collected from late May to early August from planktonic, epiphytic, epilithic, and benthic habitats in various aquatic systems in Dickinson County, Iowa. In addition, the collection has specimens of C. pediculus from a dry epilithic sample at Skunk River, Story County, Iowa taken in late July; Brewer’s Creek, Hamilton County, Iowa taken in late October; and an epilithic sample at Shell Rock River, Cerro Gordo County taken in late May.

Patrick and Reimer (1966) noted that Cocconeis pediculus is sometimes considered a pollution tolerant species, while Lange-Bertalot classified C. pediculus as pollution intolerant (Brown and Olive 1995). The EMAP assessment shows that C. pediculus can be found in a relatively wide range of environmental conditions.

Cocconeis pediculus has also been reported in periphyton samples from the upper reaches of the Cuyahoga River, which flows into Lake Erie (Brown and Olive 1995). In a study of Cladophora epiphyton in Lake Ontario, C. pediculus dominated the diatom community, which the authors hypothesized may be due to stronger attachment to the substrate or to greater resource use efficiency (Malkin et al. 2009). Other reports of C. pediculus include southern California in the Salton Sea, which C. pediculus likely entered via inflow from freshwater streams (Lange and Tiffany 2002), and the Colorado River, where C. pediculus was particularly abundant in the upstream regions of this reach near Lees Ferry and Nankoweap Creek (Hardwick et al. 1992).


Vegetative cells and auxospores of Cocconeis pediculus attached to a Cladophora filament

Credit/Source: Victoria Charibi and Marina Potapova

Initial cells of Cocconeis pediculus, with 40x objective lens

Credit/Source: Victoria Charibi and Marina Potapova

Initial cell of Cocconeis pediculus on Cladophora, with 40x objective lens

Credit/Source: Victoria Charibi and Marina Potapova

Live Cocconeis pediculus collected from a Cladophora sample in West Lake Okoboji. Scale bar is 10 μm.

Credit/Source: Catharina Grubaugh

Live Cocconeis pediculus collected from a Cladophora sample in West Lake Okoboji. Scale bar is 10 μm

Credit/Source: Catharina Grubaugh

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

Cocconeis pediculus

EMAP Response Plots

Cocconeis pediculus

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.