Aneumastus minor

Lange-Bert. 1993      Category: Symmetrical biraphid
SYNONYM(S): Navicula tuscula f. minor Hust. 1930 | Aneumastus tusculus f. minor  (Hust.) Bukht. 1995 | Aneumastus tuscula f. minor Andresen, Stoermer and Kreis 2000 

Aneumastus carolinianus


Aneumastus pseudotusculus

LM scalebar = 10 µm = 80 pixels.


Contributor: Loren Bahls - December 2012
Length Range: 18-35 µm
Width Range: 9.0-11.7 µm
Striae in 10 µm: 12-14


Valves are elliptic to broadly lanceolate with acutely rounded and sometimes slightly protracted apices. Axial area is narrow and linear in small specimens to narrowly lanceolate in larger specimens. Central area is a transverse fascia delimited by 3-4 irregularly shortened striae on each side. The raphe is weakly lateral and somewhat undulate with distinctly dilated proximal ends. Striae are radiate throughout. Areolae in the central region are transapically elongate and number 8-12 in 10 µm. Areolae are secondarily aligned in 1-2 undulate longitudinal rows alternating with longitudinal hyaline areas.

Hustedt (1930) published an illustration of Navicula tuscula fo. minor without a description and thus the name is invalid. Lange-Bertalot (1993) intended to publish Aneumastus minor in as a new combination of this taxon, but instead he effectively published a new taxon.

Original Description

Author: Lange-Bert. 1993
Length Range: 15-35 µm
Width Range: 8-12 µm
Striae in 10 µm: 11-13

Original Description

Original Images

Cite This Page:
Bahls, L. (2012). Aneumastus minor. In Diatoms of the United States. Retrieved April 24, 2018, from

Species: Aneumastus minor

Contributor: Loren Bahls

Reviewer: Mark Edlund


Hustedt, F. (1922). Die Bacillariaceen-Vegetation des Lunzer Seengebietes (Nieder-Österreich). Internationale Revue der gesamten Hydrobiologie und Hydrographie 10(1-2): 40-74, 233-270.

Hustedt, F. (1930). Bacillariophyta (Diatomeae). In: Die Subwasser Flora Mitteleuropas. (A. Pascher, ed.),10, Gustav Fischer, Jena. 468 pp.

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.

Lange-Bertalot, H. (1993). 85 Neue taxa und uber 100 weitere neu definierte Taxa erganzend zur Subwasserflora von Mittleuropa. Bibliotheca Diatomologica 27, 454 p. Cramer, Berlin, Stuttgart.

Lange-Bertalot, H. (2001). Navicula sensu stricto, 10 genera separated from Navicula sensu lato, Frustulia. Diatoms of Europe 2: 1-526.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Aneumastus minor CAS

North American Diatom Ecological Database (NADED)

NADED ID: 105007

Autecology Discussion

Aneumastus minor has been collected from mountain lakes and rivers in western Montana and from slow-moving streams on the Northwestern Great Plains. One of these sites, Big Therriault Lake (shown below) had a pH of 9.05 and a specific conductance of 176 µS/cm on the sampling date. Lange-Bertalot (2001) reports that this species prefers eutrophic, chalk-rich standing waters. Although also found in remote and relatively pristine waters, It is perhaps the most tolerant of pollution among Aneumastus species in the United States.


Big Therriault Lake, Ten Lakes Scenic Area, Kootenai National Forest, Montana: home of Aneumastus minor.

Credit/Source: Loren Bahls

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

Aneumastus minor

EMAP Response Plots

Aneumastus minor

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.