Planothidium apiculatum

(R.M.Patrick) Lange-Bert. 1999      Category: Monoraphid
BASIONYM: Achnanthes lanceolata var. apiculata R.M.Patrick 1945

Planothidium abbreviatum


Planothidium biporomum

LM scalebar = 10 µm = 40 pixels.


Contributor: Marina Potapova - December 2010
Length Range: 25-31 µm
Width Range: 9.0-12.7 µm
Striae in 10 µm: 10-12


Valves are elliptical-lanceolate with apiculate apices. The raphe valve has a large rhomboid or transversely elliptical central area. The rapheless valve has an asymmetrical central area, expanded on one side to the valve margin. This asymmetrical central area also contains a hood on the internal valve surface. The raphe is straight with expanded external proximal endings. The striae are strongly radiate on the raphe valve and slightly radiate on the rapheless valve. The striae are multiseriate.

Original Description

Basionym: Achnanthes lanceolata var. apiculata
Author: R.M.Patrick 1945
Length Range: 28 µm
Width Range: 10-11 µm
Striae in 10 µm: 10-12

Original Description

Valvae elliptico-lanceolatae, 28 μ longae, 10-11 μ latae, apicibus apiculatis. Valva superior ad instar soleae equinae effigiem in medio ostendens, pseudoraphe anguste lanceolata; striis radiantibus, 10-12 in 10 μ. Valva inferior aream axialem angustam et aream centralem rotundatam exhibens; striis validis radiantibus, 10 in 10 μ.

Original Images

Cite This Page:
Potapova, M. (2010). Planothidium apiculatum. In Diatoms of the United States. Retrieved April 26, 2018, from

Species: Planothidium apiculatum

Contributor: Marina Potapova

Reviewer: Rex Lowe


Lange-Bertalot, H. (1999). Neue Kombinationen von taxa aus Achnanthes Bory (sensu lato). Iconographia Diatomologica 6: 276-289.

Patrick, R.M. (1945). A taxonomic and ecological study of some diatoms from the Pocono Plateau and adjacent regions. Farlowia 2(2):143-221.

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

Planothidium apiculatum CAS

North American Diatom Ecological Database (NADED)

NADED ID: 155019

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

Planothidium apiculatum

EMAP Response Plots

Planothidium apiculatum

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.