Pinnularia nodosa

(Ehrenb.) W.Sm. 1856      Category: Symmetrical biraphid
BASIONYM: Navicula nodosa Ehrenb. 1838

Pinnularia microstauron


Pinnularia nodosa var. percapitata

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - March 2014
Length Range: 41-65 µm
Width Range: 7.6-9.3 µm
Striae in 10 µm: 9-11


Valves are linear with triundulate margins. The undulations are about equal in width. Apices are subcapitate and rounded. Axial areas are about one-third the valve width and become wider from the apices toward the valve center. The central area is a bilateral, sometimes a unilateral, fascia. A mottled surface of the valve is evident along either side of the raphe and continues into the central area. The raphe is lateral. Proximal raphe ends are bent to one side and terminate in small tear-shaped pores. Distal raphe fissures are shaped like question marks. Striae are weakly radiate at the valve center, becoming strongly convergent at the apices.

Two morphotypes (Krammer 2000) and variety pseudogracillima A. Mayer (1916) are pictured and described here. The morphotype or variety is indicated in the caption of each image. See also the separate page for P. nodosa var. percapitata. The description and images of “P. nodosa” presented by Patrick and Reimer (1966, p. 601, Plate 55, figs. 20, 21) appear to be of another triundulate Pinnularia.

Original Description

Basionym: Navicula nodosa
Author: Ehrenb. 1838
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Bahls, L. (2014). Pinnularia nodosa. In Diatoms of the United States. Retrieved April 25, 2018, from

Species: Pinnularia nodosa

Contributor: Loren Bahls

Reviewer: Sam Rushforth


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.

Krammer, K. (1992). Die Gattung Pinnularia in Bayern. Hoppea 52: 1-308.

Krammer, K. (2000). The genus Pinnularia. The Diatoms of Europe. Diatoms of Inland Waters and Comparable Habitats 1: 1-703.

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.

Mayer, A. (1913). Die Bacillarien der Regensburger Gewässer. Ber. Naturw. Ver. Regensburg 14: 412 pp., 30 pl.

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.

Smith, W. (1856). Synopsis of British Diatomaceae. John Van Voorst, London 1856. 2: 107pp., pls. 32-60, 61-62, A-E.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Pinnularia nodosa CAS

NCBI Genbank Taxonomy

Pinnularia nodosa NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 52048

Autecology Discussion

The specimens of P. nodosa observed here are from streams, ponds and small lakes in the Rocky Mountains and Sierra Nevada Mountains of the western United States. At these locations pH ranged from 6.02 to 7.90 and specific conductance ranged from 37 to 71 µS/cm. Krammer (2000) reports this species from waters with a low to moderate electrolyte content and pH less than 5.5, most commonly in peaty bogs and in springs.


Deadfall Lake, Trinity County, California: home of Pinnularia nodosa morphotype 2.

Credit/Source: Craig Weiland, Adventurers and Scientists for Conservation.

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

Pinnularia nodosa

EMAP Response Plots

Pinnularia nodosa

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.