Planothidium dubium

(Grunow) Round and Bukhtiyarova 1996      Category: Monoraphid
BASIONYM: Achnanthes lanceolata var. dubia Grunow 1880

Planothidium delicatulum


Planothidium frequentissimum

LM scalebar = 10 µm = 80 pixels.


Contributor: Marina Potapova - August 2011
Length Range: 7-20 µm
Width Range: 4-8.5 µm
Striae in 10 µm: 13-15


Valves are linear-elliptical with rostrate, subrostrate or narrowly subcapitate apices. The raphe valve has a linear axial area and transversely rectangular central area. The rapheless valve has a narrow, linear axial area. The asymmetric central area on the rapheless valve contains a shallow depression on the internal valve surface. The raphe is straight with expanded external proximal endings. The striae are radiate throughout both valves.

Original Description

Basionym: Achnanthes lanceolata var. dubia
Author: Grunow 1880
Length Range: 15-17 µm
Width Range: 7-7.2 µm
Striae in 10 µm: 13-14

Original Description

A. lanceolata var. dubia GRUN. (Achnanthidium delicatulum KG. ex parte?) Steht der vorigen Art sehr nahe, und unterscheidet sich fast nur durch die kurzen, breit lanzettlichen kurz zugespitzten Schaalen, und den etwas schmäleren Pseudostauros der unteren Schaalen. Querstreifen 13-14 in 0,01 mm. Länge 0,015-0,017 mm., Breite 0,007-0,0072 mm. Buchberg in Unterösterreich, Belgien.

Original Images

Cite This Page:
Potapova, M. (2011). Planothidium dubium. In Diatoms of the United States. Retrieved October 23, 2016, from

Species: Planothidium dubium

Contributor: Marina Potapova

Reviewer: Sarah Spaulding


Cleve, P.T. and Grunow, A. (1880). Beiträge zur Kenntniss der Arktischen Diatomeen. Kongliga Svenska-Vetenskaps Akademiens Handlingar, 17(2): 121 pp., 7 pls.

Round, F. E. and Bukhtiyarova, L. (1996). Four new genera based on Achnanthes (Achnanthidium) together with a re-definition of Achnanthidium. Diatom Research 11: 345-361.

Van Heurck, H. (1881). Synopsis des Diatomées de Belgique. Atlas. Ducaju & Cie., Anvers. pls 31-77.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Planothidium dubium CAS

North American Diatom Ecological Database (NADED)

NADED ID: 155021

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 dubium

EMAP Response Plots

Planothidium dubium

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.