Stauroneis rex
Bahls 2010 Category: Symmetrical biraphid
BASIONYM: Stauroneis rex Bahls 2010
LM scalebar = 10 µm = 20 pixels.
Observations
Contributor: Loren Bahls - November 2011
Length Range: 215-386 µm
Width Range: 38-60 µm
Striae in 10 µm: 12-14
Description
Valves are lanceolate and very large with blunt, broadly rounded apices. The axial area is moderately broad and linear. The central area is a rectangular stauros, often narrowing somewhat toward the valve margins. Short striae may be present in the central area. External raphe fissures are lateral. Proximal raphe ends are straight and somewhat inflated. Striae are radiate throughout. Areolae are coarse and number 11-14 in 10 µm.
Original Description
Basionym: Stauroneis rex
Author: Bahls 2010
Length Range: 215-386 µm
Width Range: 38-60 µm
Striae in 10 µm: 12-14
Original Description
Valves are very large and broadly lanceolate with blunt, broadly rounded ends. Length 215-386 µm, width 38-60 µm. Length to width ratio: 5.6-6.5. Axial area moderately broad and linear. Central area a rectangular fascia, narrowing somewhat toward the valve margins. Shortened striae may be present. External raphe fissures lateral, proximal endings somewhat inflated and straight. Terminal raphe fissures hooked, opening toward the secondary side. Striae radiate throughout, 12-14 in 10 µm. Striae puncta coarse, 11-14 in 10 µm. For measurements, n = 68 valves.
Original Images
Cite This Page:
Bahls, L. (2011). Stauroneis rex. In Diatoms of the United States. Retrieved May 18, 2013, from http://westerndiatoms.colorado.edu/taxa/species/stauroneis_rex
Species: Stauroneis rex
Contributor: Loren Bahls
Reviewer: Mark Edlund
Image Credit: Loren Bahls
- Valves very large
- Striae coarse, 12-14 in 10 µm
- Proximal raphe ends straight
- Apices bluntly rounded
Stauroneis rex is huge: 36-60 µm wide and 215-386 µm long. Valves are lanceolate with bluntly rounded apices. Proximal raphe ends are straight. Striae are coarse and number 12-14 in 10 µm.
Compare
Stauroneis phoenicenteron has smaller valves than S. rex (26-35 µm wide by 129-199 µm long) and a higher stria density (15-18 in 10 µm). It is likely that S. rex has been misidentified as S. phoenicenteron in U.S. surveys. Stauroneis baileyi, reported from Connecticut, has rhombic-lanceolate valves with narrower, more attenuated ends.
Stauroneis phoenicenteron
Stauroneis baileyi
Ehrenberg
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.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID:
Autecology Discussion
Stauroneis rex is widely distributed in ponds and small lakes in the Northern Rockies. These waters tend to be alkaline (mean pH = 7.8) with moderate concentrations of electrolytes (mean specific conductance = 194 µS/cm). In contrast, Stauroneis phoenicenteron prefers circumneutral waters (mean pH = 7.1) with low concentrations of electrolytes (mean specific conductance = 34 µS/cm).
Images
Handkerchief Lake, Flathead County, Montana: type locality of Stauroneis rex.
Credit/Source: Loren Bahls