Aneumastus tusculus

(Ehrenb.) D.G.Mann and Stickle in Round, R.M.Crawford and D.G.Mann 1990      Category: Symmetrical biraphid
BASIONYM: Navicula tuscula Ehrenb. 1840

Aneumastus rostratus


Anomoeoneis fogedii

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - December 2012
Length Range: 45-67 µm
Width Range: 16.5-20.7 µm
Striae in 10 µm: 11-12


Valves are broadly linear-elliptic with abruptly protracted, long subcapitate apices. The axial area is relatively narrow. The central area is stauroid, delimited by 4-5 irregularly shortened striae on each side. The raphe is lateral and sinuous, distinguished by a pronounced wave in the area of the Voigt faults. Proximal raphe ends are dilated. Striae are weakly radiate near the central area, becoming strongly radiate near the poles. Striae composed of complex transapically elongated areolae near the valve center. Areolae are secondarily aligned in wavy longitudinal rows. Striae near the mantles are biseriate and composed of very small areolae arranged alternately. Areolae in the central part of the valve number 8-10 in 10 µm.

Original Description

Basionym: Navicula tuscula
Author: Ehrenb. 1840
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

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

Species: Aneumastus tusculus

Contributor: Loren Bahls

Reviewer: Mark Edlund


Ehrenberg, C.G. (1840). Characteristik von 274 neuen Arten von Infusorien. Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin 1840: 197-219.

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 tusculus CAS

North American Diatom Ecological Database (NADED)

NADED ID: 105001

Autecology Discussion

Aneumastus tusculus is common in lakes in the Northern Rocky Mountains. Specimens pictured here are from three small lakes in Glacier National Park, Montana. In these lakes the pH ranges from 6.80 to 8.20 and specific conductance ranges from 168 to 315 µS/cm. In Europe, Lange-Bertalot (2001) reports this species as widespread but becoming less abundant and less frequent due to increasing pollution. It is probably the most sensitive to pollution of all the U. S. species of Aneumastus.


Governor Pond, Glacier National Park, Montana: home of Aneumastus tusculus.

Credit/Source: Loren Bahls