Visit us at

Diatoms of the United States is now known as Diatoms of North America.
This site has been redesigned and updated, and will be closing soon.

Craticula riparia

(Hust.) Lange-Bert. 1993      Category: Symmetrical biraphid
BASIONYM: Navicula riparia Hust. 1942

Craticula pampeana


Craticula sardiniana

LM scalebar = 10 µm = 80 pixels.


Contributor: David R.L. Burge | Ian Bishop - May 2015
Length Range: 30-48 µm
Width Range: 8.7-10.7 µm
Striae in 10 µm: 17-20 at valve center, 16-20 at the ends


Valves are slender and lanceolate, with rostrate to subcapitate apices. The valve face is mostly flat, however in most specimens, the apices tend to become out of focus, indicating a slightly convex valve face. Striae are parallel at the valve center, becoming convergent toward the apices. Striae near the central area may be slightly bent. Stria density isimilar but may be lower near the apices. Areolae are fine and not distinguishable in LM. The axial area is narrow along the raphe becoming slightly elliptic about the proximal raphe ends. The raphe is filiform, with slightly inflated proximal ends. The distal raphe ends are deflected unilaterally. Heribaudii valves were observed.

The iconotype of Hustedt (1942, and illustrated below) indicates a wide and distinctive central area. The drawing, however, appears to exaggerate the nature of the central area, as compared to the lectotype specimen (also shown below). We believe the specimens shown here conform to the lectotype.

Original Description

Basionym: Navicula riparia
Author: Hust. 1942
Length Range: 45 µm
Width Range: 8-10 µm
Striae in 10 µm: 20

Original Description

Navicula riparia nov. spec. Zellen dünnwandig und hyalin. Schalen landzettlich mit ziemlich spitz geschnäbelten, an den Polen wenig kopfig gerundeten Enden, um 45 µ lang, 8-10 µ breit. Raphe gerade, fadenförmig; Axialarea schmal linear, in der Mitte zu einer kleinen, elliptisch-lanzettlichen Zentralarea erweitert. Transapikal-streifen zart, etwa 20 in 10 µ, in der Mitte etwas weiter gestellt als vor den Enden, im allgemeinen fast senkrecht zur Mittellinie, im mittleren Teil wenig radial, an den Enden leicht konvergent, Pole strukturlos. Längslinien bislang nicht gesehen. Abb. 77, 78. Luzon: Vereinheit im Dagatan-Sumpf. Die Art ähnelt der Navicula halophila, von der sie sich besonders durch die Entwicklung der Zentralarea und durch die strukturlosen Polkappen unterscheidet. Die Auflösung etwa vorhandener Längslinien ist bislang nicht möglich gewesen (Hyraxpräparate!), so daß die Art nur unter Vorbehalt in diese Gruppe gestellt werden kann. Bei einer Neubearbeitung der Gattung Navicula kann die Gruppe der Naviculae orthostichae ohnehin nich beibehalten werden - wenigstens nich in ihrem bisherigen Umfange im Sinne-Cleves, - da keinesfalls alle Arten den Merkmalen entsprechen, die Cleve für diese Gruppe herausstellt.

Original Images

Cite This Page:
Burge, D., and Bishop, I. (2015). Craticula riparia. In Diatoms of the United States. Retrieved May 24, 2018, from

Species: Craticula riparia

Contributor: David R.L. Burge | Ian Bishop

Reviewer: Pat Kociolek, Sarah Spaulding


Hustedt, F. (1942). Aërophile Diatomeen in der nordwestdeutschen Flora. Bericht der Deutschen Botanischen Gessellschaft. Vol: 60, Issue: 1, pp. 55-73.

Lange-Bertalot, H. (1993). 85 Neue taxa und uber 100 weitere neu definierte Taxa erganzend zur Subwasserflora von Mittleuropa. Bibliotheca Diatomologica 27, 454 p. Cramer, Berlin, Stuttgart.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA
Original INA

California Academy of Sciences (CAS)

Craticula riparia CAS

North American Diatom Ecological Database (NADED)

NADED ID: 21016

Autecology Discussion

Records of C. riparia were confirmed in a number of sites based on archives at the Academy of Natural Sciences of Drexel University. These include specimens from state and federal monitoring projects (Badger Creek, Emmons County, ND (EPA NRSA), Apple Creek, Burleigh County, ND (EPA NRSA), an unnamed stream in central Wisconsin (EPA NRSA FW08RWI9044), Smoky Hill River, Elkader, KS (USGS NAWQA), Chopawamsic Creek, VA (Virginia DEQ) and in Moshannon Creek, PA.

In Europe, C. riparia has been reported from moderately acidic, high electrolyte streams (Lange-Bertalot 2001).


Distribution of Craticula riparia in rivers of the continental U.S. based on the National Water Quality Assessment program. Retrieved 18 March 2016.

Credit/Source: Credit/Source: USGS BioData

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

Craticula riparia

EMAP Response Plots

Craticula riparia

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.