Odontidium mesodon

(Ehrenb.) Kütz. 1844      Category: Araphid
BASIONYM: Fragilaria mesodon Ehrenb. 1839

Odontidium hyemale


Orthoseira roeseana

LM scalebar = 10 µm = 80 pixels.


Contributor: Marina Potapova - May 2009
Length Range: 10-40 µm
Width Range: 6–12 µm
Striae in 10 µm: 25-35


Valves are elliptic-lanceolate, with rounded ends. Transapical ribs are 3-6 in 10 µm. Striae are uniseriate, consisting of small poroid areolae. The axial area is linear and very narrow. A rimoportula is present at one apex. Apical pore fields are present at both apices. Frustules are rectangular in girdle view.

Original Description

Basionym: Fragilaria mesodon
Author: Ehrenb. 1839
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Potapova, M. (2009). Odontidium mesodon. In Diatoms of the United States. Retrieved April 19, 2018, from http://westerndiatoms.colorado.edu/taxa/species/Odontidium_mesodon

Species: Odontidium mesodon

Contributor: Marina Potapova

Reviewer: Sam Rushforth


Bishop, I.W. and Spaulding, S.A. (2015). Tetracyclus hinziae (Bacillariophyta), a new species from the central Cascade Mountains (WA, USA). Phytotaxa 205(3): 197-204. 10.11646/phytotaxa.205.3.7

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

Williams, D.M. (1985). Morphology, taxonomy and inter-relationships of the ribbed araphid diatoms from the genera Diatoma and Meridion (Diatomaceae: Bacillariophyta). Bibliotheca Diatomologica 8: 1-228.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Odontidium mesodon CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

This taxon is considered to be a cold water species. In western North America, it is found in streams across a range of elevation, but particularly in association with mosses. It reaches its greatest abundances in low nutrient, low conductivity waters with little human disturbance.

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

Odontidium mesodon

EMAP Response Plots

Odontidium mesodon

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.


September 19, 2017 - Transfer from the genus Diatoma to Odontidium

Re-examination of the genera Diatoma and Odontidium led Jüttner et al. (2015) to recommend the use of the name Odontidium at the generic level for taxa treated from that sub-genus of Diatoma. Refer to Jüttner et al. for an account, including a neotype designation for O. hyemale and commentary on the nomenclatural priority of Odontidium.

This taxon appeared as Diatoma mesodon Kützing 1844 in the Diatoms of the US flora from May 2010 through September 2017. As of September 2017, the taxon appears as Odontidium mesodon (Ehrenberg) Kützing 1844.