Stauroneis acuta

W.Sm. 1853      Category: Symmetrical biraphid

Stauroneis acidoclinatopsis


Stauroneis agrestis

LM scalebar = 10 µm = 20 pixels.


Contributor: Loren Bahls - November 2011
Length Range: 121-175 µm
Width Range: 21-29 µm
Striae in 10 µm: 12-15


Valves are rhombic-lanceolate and somewhat gibbous at the center, with acutely rounded apices. Pseudosepta are very prominent at the apices. The axial area is narrow near the valve apices, becoming much wider toward the central area. The central area is a wide stauros, expanding in deltoid fashion toward the valve margins. External raphe fissures are lateral, becoming filiform at the distal and proximal ends. Proximal raphe ends are weakly expanded and nearly straight. Striae are strongly radiate throughout and continue onto the valve mantle. Areolae are coarse, 12-15 in 10 µm. Cells are commonly found adherent face-to-face in short colonies. Elements of the cingulum and pseudosepta are evident in girdle view.

Original Description

Author: W.Sm. 1853
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Bahls, L. (2011). Stauroneis acuta. In Diatoms of the United States. Retrieved April 20, 2018, from

Species: Stauroneis acuta

Contributor: Loren Bahls

Reviewer: Sarah Spaulding


Bahls, L. (2010). Stauroneis in the Northern Rockies: 50 species of Stauroneis sensu stricto from western Montana, northern Idaho, northeastern Washington and southwestern Alberta, including 16 species described as new. Northwest Diatoms, Volume 4. The Montana Diatom Collection, Helena, 172 pp.

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.

Smith, W. (1853). Synopsis of British Diatomaceae. John Van Voorst, London 1853. 89 pp., pls 1-31.

Van de Vijver, B., Beyens, L. and Lange-Bertalot, H. (2004). The genus Stauroneis in Arctic and Antarctic Regions. Bibliotheca Diatomologica 50, 312 pp.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Stauroneis acuta CAS

NCBI Genbank Taxonomy

Stauroneis acuta NCBI

North American Diatom Ecological Database (NADED)

NADED ID: 62036

Autecology Discussion

Stauroneis acuta is one of two Stauroneis species in the Northern Rockies with frustules commonly found adherent face-to-face in coloneis. The other colony-forming species is Stauroneis kishinena. Stauroneis acuta is widely distributed in small lakes in both the northern and southern hemispheres (Patrick & Reimer 1966, Van de Vijver et al. 2004) and appears to prefer slightly alkaline waters with low to moderate levels of dissolved solids. It is rarely found in large numbers.


Lonesome Lake, Waterton Lakes National Park, Alberta, Canada: home of Stauroneis acuta.

Credit/Source: Barb Johnston, Parks Canada