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Melosira varians

C.Agardh 1827      Category: Centric

Melosira undulata


Meridion alansmithii

LM scalebar = 10 µm = 40 pixels.


Contributor: Marina Potapova - May 2009
Diameter: 6-30 µm
Mantle Height: 5-15 µm
Rows of areolae in 10 µm:


Cells are cylindrical, forming chains. Frustules are 6-30 µm in diameter with a mantle height of 5-15 µm. The valve face is slightly convex, covered with small spines. The mantle is covered by small granules. The frustule has a loculate structure. Numerous rimoportulae are scattered over valve face and mantle and one row of rimoportulae occurs on the mantle edge.

Original Description

Author: C.Agardh 1827
Diameter: µm
Rows of areolae in 10 µm:

Original Description

Meloseira varians, caespite fusco fluctuante, filis crassitie variis fragilissimis aureis, articulis diametro aequalibus, geniculis contractis interdum aequalibus et tunc genicula simulantibus.

Original Images

Cite This Page:
Potapova, M. (2009). Melosira varians. In Diatoms of the United States. Retrieved May 23, 2018, from

Species: Melosira varians

Contributor: Marina Potapova

Reviewer: Sam Rushforth


Agardh, C.A. (1827). Aufzählung einiger in den ostereichischen Ländern gefundenen neuen Gattungen und Arten von Algen nebst ihrer Diagnostik und beigefugten Bemerkungen. Flora oder Botanische Zeitung, Regensburg 2:625-640.

Crawford, R.M. (1978). The taxonomy and classification of the diatom genus Melosira C. A. Agardh. III. Melosira lineata (Dillw.) C.A. Ag. and M. varians C.A.Ag. Phycologia 17(3): 237-250.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Melosira varians CAS

NCBI Genbank Taxonomy

Melosira varians NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 44073

Autecology Discussion

Benthic and planktonic


Living cells of M. varians grow in long filaments

Credit/Source: Mark Edlund

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

Melosira varians

EMAP Response Plots

Melosira varians

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.