Stauroneis anceps
Ehrenberg 1843 Category: Symmetrical biraphid
BASIONYM: Stauroneis anceps Ehrenberg 1843
LM scalebar = 10 µm = 40 pixels.
Observations
Contributor: Loren Bahls - November 2011
Length Range: 48-76 µm
Width Range: 12-15 µm
Striae in 10 µm: 19-21
Description
Valves are lanceolate to linear-lanceolate. The apices are protracted and narrowly rostrate. The axial area is moderately wide and linear, expanding slightly near the central area. The central area (in Northern Rockies specimens) is a narrow rectangular stauros, hardly expanded toward valve margins and sometimes with shortened striae. The raphe is lateral. Proximal raphe ends are weakly expanded, weakly deflected, and widely spaced (they do not extend into the central area). Striae are radiate throughout. Areolae are variably spaced and number 20-28 in 10 µm.
Stauroneis anceps is one of the most commonly misidentified Stauroneis species in North America. Reichardt (1995) designated the lectotype for this species (Tafel 16, fig. 1) from a population (Sippe 1) in Ehrenberg's type material from Cayenne, French Guyana. Similar forms present in Ehrenberg's type material (Sippe 2 and Sippe 3) were later described as Stauroneis reichardtii (Lange-Bertalot et al. 2003). Specimens of S. anceps from the Northern Rockies tend to be somewhat larger, have a lower stria density and a smaller stauros than specimens of Sippe 1 in the type population, but they are otherwise quite similar. Until further work is completed, we consider the population of S. anceps described here to represent this species as described by Reichardt (1995) from Ehrenberg's type material.
Original Description
Basionym: Stauroneis anceps
Author: Ehrenberg 1843
Length Range: 40-70 µm
Width Range: 10-13 µm
Striae in 10 µm: 22-24
Original Description
Original Images
Cite This Page:
Bahls, L. (2011). Stauroneis anceps. In Diatoms of the United States. Retrieved May 20, 2013, from http://westerndiatoms.colorado.edu/taxa/species/stauroneis_anceps
Species: Stauroneis anceps
Contributor: Loren Bahls
Reviewer: Sarah Spaulding
Image Credit: Loren Bahls
- Apices protracted and narrowly rostrate
- Valves lanceolate to linear-lanceolate
- Stauros narrow and rectangular
Stauroneis anceps has moderately large lanceolate to linear-lanceolate valves, 12-15 µm wide. The apices are distinctly protracted, narrow and rostrate. The stauros (in specimens from the Northern Rockies) is relatively narrow and rectangular. Proximal raphe ends are weakly expanded and deflected.
Compare
Stauroneis anceps may be distinguished from other Stauroneis species of similar shape and size by its long, narrow, rostrate apices.
Stauroneis acidoclinata
Stauroneis amphicephala
Stauroneis reichardtii
Stauroneis ancepsfallax
Stauroneis fluminea
Patrick & Freese
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.
Ehrenberg, C.G. (1843). Verbreitung und Einfluß des mikroskopischen Lebens in Süd- und Nord-Amerika. Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin, 1841: 291-445, 4 Tafel.
Lange-Bertalot, H., Cavacini, P., Tagliaventi, N. and Alfinito, S. (2003). Diatoms of Sardinia: Rare and 76 new species in rock pools and other ephemeral waters. Iconographia Diatomologica 12, 438 pp.
Reichardt, E. (1995). Die Diatomeen (Bacillariophyceae) in Ehrenbergs Material von Cayenne, Guyana Gallica (1843). Volume 1, Iconographia Diatomologica (H. Lange-Bertalot, ed.). Koeltz Scientific Books, Konigstein.
Links & ID's
Index Nominum Algarum (INA)
California Academy of Sciences (CAS)
North American Diatom Ecological Database (NADED)
NADED ID: 62002
Autecology Discussion
In the Northern Rockies, Stauroneis anceps is found in lakes and ponds with circumneutral pH (mean pH = 6.9) and very low specific conductance (mean SC = 17 µS/cm).
Images
Bloody Dick Pond #2, Beaverhead County, Montana: Home of Stauroneis anceps
Credit/Source: Loren Bahls
EMAP Assessment
Sampling for the Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming). Over 1200 sites on streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.
EMAP Distribution
Stauroneis anceps
Distribution
The distribution map represents the relative abundance of this Stauroneis anceps in the western EMAP study. Relative abundance is a measure of the proportion of cells of this species based on a "fixed count" of 300 total diatom cells counted and identified. Each of the western EMAP sample sites is shown, either with a black dot for sites where Stauroneis anceps was not recorded, or with a red circle indicating the relative abundance of Stauroneis anceps.
Note that the size of the proportional symbols varies between species to help show both abundant and rare species.
Scale for the map to the left
EMAP Response Plots
Stauroneis anceps
EMAP citations
Results are published in:
Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.
Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.
Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.