Ehrenberg 1843 Category: Araphid
BASIONYM: Staurosira construens Ehrenberg 1843
Contributor: Eduardo Morales - October 2010
Length Range: 6-15 µm
Width Range: 5-9 µm
Striae in 10 µm: 14-16
Valves are cruciform, 5-9 µm wide and 6-15 µm long. Valves with rostrate to subcapitate ends. The central margin is inflated and narrowly or widely curved. Valve face flat, or slightly undulate due to raised costae. The valve face/mantle junction forms a sharp angle. Abvalvar edge of mantle parallel to the valve face/mantle junction. In girdle view, frustules are rectangular, but show the prominent inflation and form ribbon-like colonies, joined by linking spines. The colonies are attached to the substratum at one end by a frustule attached by a mucilage pad, or colonies may be planktonic. The axial area is linear to lanceolate, much wider at the valve central area in some specimens. Striae are distinct, alternate, and composed of lineolae decreasing in size from the valve face/mantle edge to both the central sternum and the valve mantle; 14-16 in 10 µm. The lineolae bear finely branched volae. Striae are curved and vary from parallel to radiate in the central area to slightly radiate to parallel toward the valve ends. Sometimes shorter striae intercalated with longer striae are present toward the valve face edge in the central inflations. Striae extend onto the valve mantle. The costae are broad. Spines are spatulate, hollow and some possess terminal digitations that connect to the neighboring valve lineolae. Spines are present along the valve face edge, except at the apices, and always located on the costae, between striae. Well-developed, ocellulimbus type, apical pore ﬁelds with round poroids are present. Poroids are each frequently surrounded by a whitish rim, presumably siliceous in nature. Apical pore fields are located on the transition between valve face/mantle. Rimoportula are absent. Scab-like structures, or blisters, are absent. Copulae, or girdle bands are open and do not bear perforations. Valvocopula only slightly wider than copulae.
Populations from North America often contain morphological variants that occur together in a single locality. It is uncertain whether these variants are the product of sexual reproduction occurring in a single population, ecotypes resulting from adaptation to local environmental conditions, or whether they in fact represent different species. The type material of Ehrenberg also contains such variation (P. Hamilton, pers. comm.).
Basionym: Staurosira construens
Author: Ehrenberg 1843
Length Range: µm
Striae in 10 µm:
Sr. construens, testula minima laevis, angulis productis subaequalibus.
Ehrenberg, C.G. (1841). Über Verbreitung und Einfluss des mikroskopischen Labens in Süd- und Nordamerika. Bericht über die zur bekanntmachung geeigneten Verhandlungen der Königlich-Preussischen Akademie der Wissenschaften zu Berlin. p. 144. (first mention).
Ehrenberg, C.G. (1854). Mikrogeologie. Einundvierzig Tafeln mit über viertausend grossentheils colorirten Figuren, Gezeichnet vom Verfasser. Voss, Leipzig., Pl. 5, II, fig. 23 (iconotype).
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.
Marciniak, B. (1982). Late Glacial and Holocene new diatoms from a glacial Lake Przedni Staw in the Przedni Stawów Polskich Valley, Polish Tatra Mts. Acta Geol. Acad. Sci. Hung. 25: 161-171.
Morales, E.A. (2006). Staurosira incerta (Bacillariophyceae) a new fragilarioid taxon from freshwater systems in the United States with comments on the structure of girdle bands in Staurosira Ehrenberg and Staurosirella Williams et Round. In: Manoylov, K. & Ognjanova, N. (Eds.). Fossil and Recent Phycological studies. Dobrina Temniskova-Topalova. Festschrift. pp. 133-145. Pensoft Publishers and University Publishing House. Sophia, Bulgaria.
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.
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.