Stauroneis pax

L.L.Bahls 2010      Category: Symmetrical biraphid

REPORTED AS: Stauroneis spec. 1 (Van de Vijver et al. 2004) 

Stauroneis neohyalina


Stauroneis phoenicenteron

LM scalebar = 10 µm = 40 pixels.


Contributor: Loren Bahls - December 2011
Length Range: 62-90 µm
Width Range: 13.9-17.5 µm
Striae in 10 µm: 18-20


Valves are elliptic-lanceolate to linear-lanceolate with subcapitate apices. The axial area is linear, about three times wider than the raphe, and expands slightly near the central area. The central area is very wide at the valve margins and shaped like a bow tie. One to several short striae occur at each margin of the central area. Raphe branches are lateral but become filiform towards the distal and proximal ends. Distal raphe ends are hooked in the same direction. Proximal raphe ends are nearly straight and tipped with unexpanded central pores. Striae are somewhat wavy and strongly radiate throughout. Areolae are easily distinguished in LM and number 18-20 in 10 µm.

Original Description

Author: L.L.Bahls 2010
Length Range: 62-90 µm
Width Range: 13.9-17.5 µm
Striae in 10 µm: 18-20

Original Description

Valves elliptic-lanceolate to linear-lanceolate with protracted subcapitate ends. Length 62-90 µm, width 13.9-17.5 µm. Axial area narrow, linear, widening close to the central area. Central area shaped like a bow tie, much wider at valve margins. One to several shortened striae on each margin. Raphe lateral, becoming filiform toward the endings of each branch. Distal ends hooked in the same direction, proximal endings nearly straight and tipped with unexpanded central pores. Striae somewhat wavy and strongly radiate throughout, 18-20 in 10 µm. Striae puncta easily distinguished in LM, 18-20 in 10 µm. For measurements, n = 9 valves.

Original Images

Cite This Page:
Bahls, L. (2011). Stauroneis pax. In Diatoms of the United States. Retrieved April 22, 2018, from

Species: Stauroneis pax

Contributor: Loren Bahls

Reviewer: Mark Edlund


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 Freese, L.R. (1961). Diatoms (Bacillariophyceae) from Northern Alaska. Proceedings of the Academy of Natural Sciences of Philadelphia 112(6):129-293.

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 pax CAS

North American Diatom Ecological Database (NADED)


Autecology Discussion

In the Northern Rockies, Stauroneis pax has been recorded from two lakes, a river, and a spring seep. All but one of these sites lies within the Waterton/Glacier International Peace Park. The remaining site, Lake Lavale, is in the Bob Marshall Wilderness about 100 km south of Glacier National Park. The pH of these waters ranges from 8.0 to 8.2 and specific conductance ranges from 149 to 183 µS/cm. Van de Vijver et al. (2004) reported this taxon from the Russian Arctic, where it was found in “a small, very shallow ditch, completely colonized by green algae”.


Lake Levale, Bob Marshall Wilderness, Lewis & Clark County, Montana: home of Stauroneis pax.

Credit/Source: Loren Bahls