Lange-Bertalot and Werum 2004 Category: Symmetrical biraphid
BASIONYM: Stauroneis pseudagrestis Lange-Bertalot and Werum 2004
Contributor: Loren Bahls - May 2012
Length Range: 27-43 µm
Width Range: 6.4-9.4 µm
Striae in 10 µm: 23-26
Valves are lanceolate with capitate apices. The axial area is narrow and widens very little or not at all near the central area. The stauros is a very broad, with curved striae on the margins. The raphe is filiform with unexpanded proximal ends that are bent slightly in the same direction. Striae are strongly radiate. Areolae are difficult to resolve in LM and number about 30 in 10 µm.
Basionym: Stauroneis pseudagrestis
Author: Lange-Bertalot and Werum 2004
Length Range: 26-35 µm
Width Range: 6.5-7.0 µm
Striae in 10 µm: 24-27
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.
Werum, M. and Lange-Bertalot, H. (2004). Diatoms in springs, from Central Europe and elsewhere under the influence of hydrogeology and anthropogenic impages. Iconographia Diatomologica 13: 1-417.
Stauroneis pseudagrestis is uncommon in the U. S. and reported to date only from three small lakes and ponds in southwestern Montana. Here it prefers slightly alkaline water (pH 7.34-7.83) with low specific conductance (31-41 µS/cm). This species was described from springs in Germany.
Bloody Dick Pond No. 6, Beaverhead County, Montana: home of Stauroneis pseudagrestis.
Credit/Source: Loren Bahls