Stauroneis subborealis
Bahls 2010 Category: Symmetrical biraphid
BASIONYM: Stauroneis subborealis Bahls 2010
LM scalebar = 10 µm = 40 pixels.
Observations
Contributor: Loren Bahls - December 2011
Length Range: 46-142 µm
Width Range: 9-24 µm
Striae in 10 µm: 17-20
Description
Valves are linear in small specimens to lanceolate in larger specimens, with protracted and broadly rounded apices. The axial area is narrow and widens slightly near the central area. The stauros is narrow, somewhat expanded toward the valve margins, and occasionally contains short striae at the margins. Raphe branches are lateral. Proximal raphe ends are inflated and curved. Terminal raphe fissures are hooked. Striae are radiate throughout. Areolae number 18–22 in 10 µm.
Original Description
Basionym: Stauroneis subborealis
Author: Bahls 2010
Length Range: 46-142 µm
Width Range: 9-24 µm
Striae in 10 µm: 17-20
Original Description
Valves are linear in small specimens to lanceolate in larger specimens, with protracted and broadly rounded apices. Length 46–142 µm, width 9–24 µm. Length to width ratio: 4.9-6.6. Axial area narrow, widening slightly near the central area. Transverse fascia narrow, somewhat expanded toward the valve margins, occasionally containing short striae. Raphe fissures lateral, proximal endings inflated and curved. Terminal raphe fissures hooked. Striae radiate throughout, 17–20 in 10 µm. Striae puncta 18–22 in 10 µm. For measurements, n = 31 valves.
Original Images
Cite This Page:
Bahls, L. (2011). Stauroneis subborealis. In Diatoms of the United States. Retrieved June 20, 2013, from http://westerndiatoms.colorado.edu/taxa/species/stauroneis_subborealis
Species: Stauroneis subborealis
Contributor: Loren Bahls
Reviewer: Mark Edlund
Image Credit: Loren Bahls
- Valves linear in small specimens, lanceolate in large specimens
- Apices protracted and broadly rounded
- Proximal raphe ends curved, inflated
- Striae 17-20 in 10 µm
- Areolae 18-22 in 10 µm
The small specimens are linear, while large specimens are lanceolate; 46-142 µm in length. Apices are protracted and broadly rounded. Proximal raphe ends are curved and inflated. Striae are radiate throughout and number 17-20 in 10 µm. Areolae number 18-22 in 10 µm.
Compare
Larger specimens of S. subborealis may be distinguished from S. beeskovea by more widely spaced and less radiate striae, a smaller length to width ratio, and proximal raphe ends that are curved rather than straight. Stauroneis subborealis is smaller than S. subaustralis (46–142 µm long, compared to 85–165) and has a higher stria density (17–20 in 10 µm, rather than 16 in 10 µm) and areola density (18–22 in 10 µm, compared to 16–18 in 10 µm). Smaller, linear specimens of S. subborealis are similar in size and valve outline to S. subgracilis, but US populations of S. subborealis also include much larger specimens with a lanceolate shape. Stauroneis pergracilis has narrower and more distinctly protracted apices than S. subborealis. Stauroneis gracilis has elliptic-lanceolate valves, not linear or strictly lanceolate valves.
Stauroneis beeskovea
Stauroneis gracilis
Stauroneis subaustralis
Van de Vijver & Lange-Bertalot
Stauroneis subgracilis
Lange-Bertalot & Krammer
Stauroneis pergracilis
Van de Vijver & Lange-Bertalot
Citations
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)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID:
Autecology Discussion
Stauroneis subborealis has been found in a few fens, ponds, and small lakes in western Montana. The pH of these waters ranges from 6.2 to 9.1 and specific conductance ranges from 10 to 257 µS/cm.
Images
Drosera Fen, Indian Meadows Research Natural Area, Helena National Forest, Montana: type locality for Stauroneis subborealis.
Credit/Source: Loren Bahls