Bahls 2012 Category: Symmetrical biraphid
BASIONYM: Stauroneis thompsonii Bahls 2012
REPORTED AS: Stauroneis aff. catharinae (Bahls 2010, p. 61, figs. 1-5)
Contributor: Loren Bahls - October 2012
Length Range: 81-124 µm
Width Range: 16.3-23.5 µm
Striae in 10 µm: 15-18
Valves are lanceolate with rounded, unprotracted apices. A relatively deep pseudoseptum occupies each apex. The axial area is narrowly lanceolate and widens gradually to the central area. Central stauros is nearly rectangular, expanding somewhat toward the valve margins, and positioned diagonally at a low angle to the transapical axis. The raphe is distinctly lateral with straight proximal ends that are weakly inflated. Striae are radiate throughout. Areolae are relatively coarse and number 12-16 in 10 µm.
Basionym: Stauroneis thompsonii
Author: Bahls 2012
Length Range: 88-105 µm
Width Range: 16.3-17.5 µm
Striae in 10 µm: 17-18
Valves lanceolate with rounded, unprotracted apices. A deep pseudoseptum occupies each apex (Fig. 24). Valve length 88–105 µm; valve width 16.3–17.5 µm. Raphe lateral with straight proximal ends, slightly inflated. Distal raphe ends hooked to same side. Axial area narrowly lanceolate, widens gradually towards central area. Central stauros nearly rectangular and placed somewhat diagonally to apical axis. Striae radiate throughout, 17–18 in 10µm. Areolae in striae 12-15 in 10 µm.
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.
Bahls, L. (2012). Five new species of Stauroneis (Bacillariophyta, Stauroneidaceae) from the northern Rocky Mountains, USA. Phytotaxa 67: 1-8.
Stauroneis thompsonii is known so far only from the type locality, where it is uncommon. It was first collected by the author in September 1990. In September 2012, the author returned to the same location and collected another sample containing this species. On the latter date, water temperature measured 12.5 C, pH was 8.83, and specific conductance was 107 µS/cm.
Upper Wolverine Lake, Ten Lakes Scenic Area, Kootenai National Forest, Lincoln County, Montana: type locality of Stauroneis thompsonii.
Credit/Source: Loren Bahls