Stauroneis submarginalis

Bahls 2010      Category: Symmetrical biraphid
BASIONYM: Stauroneis submarginalis Bahls 2010

Stauroneis subborealis


Stauroneis supergracilis

LM scalebar = 10 µm = 20 pixels.


Contributor: Loren Bahls - December 2011
Length Range: 140-186 µm
Width Range: 23-35 µm
Striae in 10 µm: 15-17


Valves are broadly lanceolate with slightly protracted and broadly rounded apices. A narrow longitudinal line, visible in LM, runs parallel to and 2–3 µm inside the valve/mantle margin. The axial area is narrow and widens slightly near the central area. The central area is s narrow, rectangular stauros, slightly expanded towards the valve margins where short striae are often present. Raphe branches are lateral with proximal ends inflated and curved. Terminal raphe fissures are hooked. Striae are radiate throughout. Areolae number 16–20 in 10 µm.

Original Description

Basionym: Stauroneis submarginalis
Author: Bahls 2010
Length Range: 140-186 µm
Width Range: 23-35 µm
Striae in 10 µm: 15-17

Original Description

(Differential diagnosis compared to Stauroneis rex): Valves are broadly lanceolate with slightly protracted, broadly rounded apices. Length 140–186 µm (not >225 µm), breadth 23–35 µm (not >35 µm). Length to width ratio: 5.0-6.4. A narrow longitudinal line, visible in LM, runs parallel to and 2–3 µm inside the valve margins. Axial area narrow, widening slightly near the central area. Transverse fascia narrow, rectangular, slightly expanded toward the valve margins. Fascia often with short striae. Raphe fissure lateral, proximal ends inflated and curved (not straight). Terminal raphe fissures hooked. Striae radiate throughout, 15–17 (not 12–14) in 10 µm. Striae puncta 16–20 (not 11–14) in 10 µm. For measurements, n = 22 valves.

Original Images

Cite This Page:
Bahls, L. (2011). Stauroneis submarginalis. In Diatoms of the United States. Retrieved October 22, 2017, from

Species: Stauroneis submarginalis

Contributor: Loren Bahls

Reviewer: Pat Kociolek


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.

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 submarginalis CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

Stauroneis submarginalis has been found in several small lakes and wetlands in western Montana, northern Idaho, eastern Washington, and southern Alberta. The pH of these waters ranges from 6.2 to 8.6 and specific conductance ranges from 10 to 92 µS/cm.


Loren Bahls at Drosera Pond, Indian Meadows Research Natural Area, Helena National Forest, Montana: type locality of Stauroneis submarginalis.

Credit/Source: John Pierce