Aneumastus rostratus

(Hust.) Lange-Bert. 2001      Category: Symmetrical biraphid
BASIONYM: Navicula tuscula var. rostrata Hust. 1911

REPORTED AS: Navicula tuscula (Patrick and Reimer 1966, p. 539 [in part], pl. 52, fig. 7) | Navicula tuscula (Krammer and Lange-Bertalot 1986, p. 234 [in part], fig. 24: 1; figs. 81: 3,8) 

Aneumastus pseudotusculus


Aneumastus tusculus

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - December 2012
Length Range: 43-64 µm
Width Range: 16.9-19.6 µm
Striae in 10 µm: 11-12


Valves are broadly lanceolate to elliptic-lanceolate with rostrate apices. Axial area is narrow and linear. Central area is a rectangular transverse fascia delimited by 3-5 unevenly shortened striae on each side. The raphe is filiform to weakly lateral and straight to slightly undulate. Proximal raphe ends are dilated. Striae are radiate throughout. Areolae are transversely elongate in the central region and irregularly spaced where they number 8-10 in 10 µm, becoming more densely and evenly packed near the valve margin. Areolae are secondarily aligned in wavy longitudinal rows.

Original Description

Basionym: Navicula tuscula var. rostrata
Author: Hust. 1911
Length Range: µm
Striae in 10 µm:

Original Description

Valva elliptica, apicus subrostratis. Tab. III, Fig. 22. 880/1.

Original Images

Cite This Page:
Bahls, L. (2012). Aneumastus rostratus. In Diatoms of the United States. Retrieved April 20, 2018, from

Species: Aneumastus rostratus

Contributor: Loren Bahls

Reviewer: Mark Edlund


Hustedt, F. (1911). Beiträge zur Algenflora von Bremen. IV. Bacillariaceer aus der Wumme. Abhandlungen des Naturwissenschaftlichen Verein zu Bremen 20(2): 257-315, Tafs 2-3.

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

Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Simonsen, R. (1987). Atlas and Catalogue of the Diatom Types of Friedrich Hustedt. J. Cramer, Berlin & Stuttgart 1: 525 pp.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Aneumastus rostratus CAS

North American Diatom Ecological Database (NADED)

NADED ID: 44238

Autecology Discussion

Aneumastus rostratus has been collected from several lakes and ponds in Glacier National Park, Montana and Waterton Lakes National Park, Alberta. Here pH ranges from 7.08 to 8.54 and specific conductance ranged from 92 to 183 µS/cm. In Europe, Lange-Bertalot (2001) reports optimum conditions for this species in electrolyte-rich to brackish waters near the coasts.


Redrock Lake, Glacier National Park, Montana: home of Aneumastus rostratus.

Credit/Source: Loren Bahls