Stephanodiscus niagarae

Ehrenb. 1845      Category: Centric

Stephanodiscus minutulus


Stephanodiscus oregonicus

LM scalebar = 10 µm = 40 pixels.


Contributor: Anna Mengjie Yu - June 2011
Diameter: 21-70 µm
Rows of areolae in 10 µm:


Cells discoid or barrel-shaped , with concentrically undulate valves that produce either a convex (scutate) or concave (lacunate) valve face. Valves appear undulate in girdle view in the LM. A ring of spines is present around the valve face, occuring in a single row at the end of every second or third costa at the junction of the valve face and mantle. Areolae are arranged in radiating striae separated by raised hyaline costae. In the valve center the striae are uniseriate, towards the margin striae become biseriate or triseriate. Areolae appear round or angular in the SEM, and round in high focus in LM. Convex domed cribra close the internal opening of the areolae. Fascicles closely spaced, separated by thin costae (also termed hyaline interfascicle). There are 7-9 fascicles in 10 µm, and 11-20 areolae in 10 µm. Every second or third interfascicle with a spine continues over the edge of the valve onto the valve mantle.

Spines are curved and tapered, with a sharply pointed tip. Marginal fultoportulae are present, arranged in a ring around the mantle, always occurring beneath each spine; central fultoportulae occur at the center of the valve face, singly or in a ring. The fultoportulae have 3 satellite pores and external buttresses. One or a few rimoportulae occur on the mantle-face junction. The rimoportulae have tubular external extensions that superficially resembles the spines. The rimortulae, however, are positioned slightly abvalvar the ring of spines. Rimoportulae are difficult to distinguish in LM, but they are shorter, straighter and less tapered than spines.

Original Description

Author: Ehrenb. 1845
Diameter: 62.7 µm
Rows of areolae in 10 µm:

Original Description

Stephanodiscus Niagarae: St. major, nummiformis planus, denticulis marginalibus utrinque (saepe 64) acutis, disci radiis (saepe 64) granulatis, centro granulato non radiato, Diam. -1/36’’’. Vivus in Niagara

Original Images

Cite This Page:
Yu, A. (2011). Stephanodiscus niagarae. In Diatoms of the United States. Retrieved April 23, 2018, from

Species: Stephanodiscus niagarae

Contributor: Anna Mengjie Yu

Reviewer: Mark Edlund


Edlund, M.B. and Stoermer, E.F. (1991). Sexual reproduction in Stephandiscus niagarae (Bacillariophyta). Journal of Phycology 27(6): 780-793. 10.1111/j.0022-3646.1991.00780.x

Håkansson, H. and Meyer, B. (1994). A comparative study of species in the Stephanodiscus niagarae-complex and a description of S. heterostylus sp. nov. Diatom Research 9(1): 65-85. 10.1080/0269249X.1994.9705288

Round, F.E. (1981). The diatom genus Stephanodiscus: An electron-microscopic view of the classical species. Arch. Protistenk 124: 455-470.

Stoermer, E.F. and Sicko-Goad, L. (1985). A comparative ultrastructural and morphometric study of six species of the diatoms genus Stephanodiscus. Journal of the Great Lakes Research 7 (1): 125-135.

Theriot, E.C. (1987). Principal component analysis and taxonomic interpretation of environmentally related variation in silicification in Stephanodisus (Bacillariophyceae). British Phycology Journal, 22: 359-373.

Theriot, E.C. (1988). Taxonomy of the diatom Stephanodiscus niagarae from a fossil deposit in Jingyu County, Jilin Province, China. Diatom Research 3(1): 159-167.

Theriot, E. and Stoermer, E.F. (1981). Some aspects of morphological variation in Stephanodiscus niagarae (Bacillariophyceae). Journal of Phycology 17: 64-72.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Stephanodiscus niagarae CAS

NCBI Genbank Taxonomy

Stephanodiscus niagarae NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 64001

Autecology Discussion

Stephanodiscus niagarae was collected in a plankton tow sample from Grove Lake, Antelope County, Nebraska. The lake habitat temperature was 20.7°C, the water conductivity reached 293 µS/cm, DO showed 7.1 mg/L, and pH showed 9. In specimens from the Iowa Lakeside Lab Herbarium, S. niagarae was found in planktonic and epipelic samples of West Lake Okoboji, Little Miller’s Bay, Fork Des Moines River, and North Spirit Lake in Iowa.

Stephanodiscus niagarae Ehrenberg is a common living and fossil diatom in North America, and occasionally dominates phytoplankton assemblages in lakes throughout North America. Populations in the Great Lakes has been reported ranging from 20 µm to > 100 µm in diameter (Theriot 1983 in Stoermer & Sicko-Goad, 1985). It is abundant in North American Quaternary fossil deposits and also has been reported as a fossil from Asia, Africa, and Europe. Stephanodsicus niagarae was found in a paleolacustrine deposit in Jingyu County, Jilin Province, northeastern China; the central fultoportula count is roughly intermediate between that for living North American specimens of S. niagarae and fossil European specimens of the type of S. rotula, suggesting the possibility of evolutionary intermediacy (Theriot et al., 1988). A study of correlation matrix of 16 characters of 129 S. niagarae specimens from 14 lentic North American habits revealed variation in silification; larger valves more heavily silicified than smaller ones, and specimens from lakes with high ambient silicon: phosphorus ratios were more heavily silicified (Theriot, 1987).


Grove Lake View, Nebraska

Credit/Source: Anna Yu

Live cells, girdle view and valve view

Credit/Source: Anna Yu

Live cells, girdle view and valve view

Credit/Source: Image by Anna Yu

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

Stephanodiscus niagarae

EMAP Response Plots

Stephanodiscus niagarae

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.