Psammothidium curtissimum

(J.R.Carter) Aboal in Aboal, Alvarez-Cobelas, Cambra and Ector 2003      Category: Monoraphid
BASIONYM: Achnanthes curtissima J.R.Carter 1963

Psammothidium chlidanos


Psammothidium daonense

LM scalebar = 10 µm = 80 pixels.


Contributor: Marina Potapova - August 2010
Length Range: 5-9 µm
Width Range: 3.5-4.0 µm
Striae in 10 µm: 27-31


Valves are elliptical to linear-elliptical. The raphe valve has a linear axial area and a small transversely elongated central area formed by one to three shortened striae on each side. The raphe is straight, without terminal fissures. The central and terminal raphe ends are slightly expanded externally. The central raphe ends curve toward opposite sides internally. The rapheless valve has a linear-lanceolate or narrowly rhomboid axial area, and a small transversely elongated central area. Striae are radiate on both valves, 27-31 in 10 µm, interrupted at the valve margin. One row of areolae is present on the mantle of both valves. External openings of the areolae on the raphe valve are large, square or rectangular, occasionally elongated. Such openings on the rapheless valve are usually small, circular to silt-like. Internal openings of the areolae on the faces of both valves are square, on the mantle they are elliptical.

Original Description

Basionym: Achnanthes curtissima
Author: J.R.Carter 1963
Length Range: 7 µm
Width Range: 3 µm
Striae in 10 µm: 30

Original Description

Valve oval with rounded ends about 7 μ long and 3 μ wide. Raphe valve with straight delicate raphe and approximate central pores, longitudinal space narrow lanceolate, central space wanting, striae radiate throughout about 33 in 10 μ the central one on each side being curtailed. Rapheless valve with lanceolate pseudo-raphe and no central space, striae less radiate than those of the complementary valve about 30 in 10 μ.

Original Images

Cite This Page:
Potapova, M. (2010). Psammothidium curtissimum. In Diatoms of the United States. Retrieved April 19, 2018, from

Species: Psammothidium curtissimum

Contributor: Marina Potapova

Reviewer: Sarah Spaulding


Aboal, M., Alvarez-Cobelas, M., Cambra, J. and Ector, L. (2003). Floristic list of non marine diatoms (Bacillariophyceae) of Iberian Peninsula, Balearic Islands, and Canary Islands. Updated taxonomy and bibliography. In: A. Witkowski (ed.), Diatom Monographs. A.R.G. Gantner Verlag K.G., 4: 639 pp.

Carter, J.R. (1963). Some new diatoms from British waters. Journal of the Quekett Microscopical Club 29(8):199-203.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Psammothidium curtissimum CAS

North American Diatom Ecological Database (NADED)

NADED ID: 186021

Autecology Discussion

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

Psammothidium curtissimum

EMAP Response Plots

Psammothidium curtissimum

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.