Craticula cuspidata

(Kütz.) D.G.Mann 1990      Category: Symmetrical biraphid
BASIONYM: Frustulia cuspidata Kütz. 1833
SYNONYM(S): Navicula cuspidata (Kütz.) Kütz. 1844 | Navicula cuspidata var. heribaudii Perag. in Hérib. 1893 

Craticula coloradensis


Craticula halophila

LM scalebar = 10 µm = 20 pixels.


Contributor: Lauren Fuelling | Gina LaLiberte - June 2011
Length Range: 95-157 µm
Width Range: 24-36 µm
Striae in 10 µm: 12-14 transverse, 24-26 longitudinal


Valves are rhombic-lanceolate and widest at the center of the valve before tapering to narrow apices. Striae are parallel and equidistant throughout the entire valve, with thin transapical costae intersecting perpendicular to the longitudinal striae forming an orthostichous pattern. Striae are composed of small, elliptic areolae, approximately 12-14 in 10 µm in the transverse direction and 24-26 in 10 µm longitudinally. The axial area is narrow with a slightly widened central area with slightly concave margins. The raphe is filiform. The proximal raphe ends are expanded and either straight, or slightly hooked in the same direction. The distal raphe ends form hooks, deflected in the same direction.

This species is polymorphic and forms modified valves termed craticulae and heribaudii valves, as in other species within the genus Craticula. The polymorphic valves are formed as the result of increases in salinity. Craticular valves possess a central rib with plates that extend transapically across the valve, but the ribs lack a consistent definite shape or pattern. Craticula valves lack a raphe system. Heribaudii valves have radial, punctate striae that appear to retain an equal distance between striae. Unlike the craticula valves, heribaudii valves possess a simple raphe system similar to vegetative valves.

Patrick and Reimer (1966, plate 43, fig 10) illustrate a capitate form within the species Craticula cuspidata. However, Lange-Bertalot (2001) note that this smaller morph is incorrectly included within C. cuspidata, and should be recognized as the distinct species C. ambigua (Ehrenberg) Mann 1990. This web flora also recognizes C. ambigua. Note, however, that many previous reports of C. cuspidata in North America include C. ambigua.

Original Description

Basionym: Frustulia cuspidata
Author: Kütz. 1833
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Fuelling, L., and LaLiberte, G. (2011). Craticula cuspidata. In Diatoms of the United States. Retrieved April 20, 2018, from

Species: Craticula cuspidata

Contributor: Lauren Fuelling | Gina LaLiberte

Reviewer: Pat Kociolek


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.

Kützing, F.T. (1833). Synopsis Diatomacearum oder Versuch einer systematischen Zusammenstellung der Diatomeen. Linnaea 8(5): 529-620, pls. XIII-XIX.

Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.

Mann, D.G. and Stickle, A. (1991). The genus Craticula. Diatom Research 6: 79-107. 10.1080/0269249X.1991.9705149

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.

Round, F.E., Crawford, R.M. and Mann, D.G. (1990). The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.

Schmid, A.M. (1979). Influence of environmental factors on the development of the valve in diatoms. Protoplasma 99: 99-115. 10.1007/BF01274072

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Craticula cuspidata CAS

NCBI Genbank Taxonomy

Craticula cuspidata NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 21004

Autecology Discussion

Craticula cuspidata is found in various freshwater benthic habitats, and can often be found in epiphytic, epipelic, and epilithic substrata. It is tolerant of a range of water quality conditions, but sudden environmental changes in ion balance or salinity may cause the formation of resting spores and the morphologically differing “craticula” and “heribaudii” valves (Schmid 1979; Mann and Stickle 1991). Populations have been reported throughout the United States.


Live Craticula cuspidata cell with chloroplasts appressed to the valve mantle.

Credit/Source: L. Fuelling

Live C. cuspidata cell at an oblique angle, displaying small, spherical lipids and two larger volutin granules.

Credit/Source: L. Fuelling

Live Craticula cuspidata cell with two distinctive volutin granules, chloroplasts appressed to the valve mantle. The simple raphe system is also visible.

Credit/Source: L. Fuelling

Open waters of Beck’s Canal, Dickinson Co., Iowa, bordered by epiphytic and epipelic habitats where populations of C. cuspidata are commonly found.

Credit/Source: L. Fuelling

Craticula cuspidata inhabits various benthic substrata, and grows epiphytically on duckweed (Lemna spp.).

Credit/Source: L. Fuelling

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 cuspidata

EMAP Response Plots

Craticula cuspidata

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.