Lange-Bertalot 2000 Category: Symmetrical biraphid
BASIONYM: Navicula menisculus var. grunowii Lange-Bertalot 1993
Valves are lanceolate, 4.2-4.7 µm wide and 11.5-16 µm long. The raphe is filiform. The axial area is narrow and linear. The central area is relatively small, oval to slightly asymmetrical. Striae are radiate and curved near the valve center. Striae become convergent at the valve apices. Striae are lineolate, 16-22 in 10 µm. Lineolae 45-52 in 10 µm.
Note that lineolate striae are not evident in specimens from Utah streams illustrated here. We have, however, observed lineolate striae in other North American populations. Lineolate striae are also clearly evident in the light micrographs of the type material of Lange-Bertalot though the lineolae in the SEM of a specimen from the type material exceed resolution of the LM. The variation in lineolate striae is a topic that deserves further investigation.
Basionym: Navicula menisculus var. grunowii
Author: Lange-Bertalot 1993
Length Range: 11-25 µm
Width Range: 6-7.5 µm
Striae in 10 µm: 10.5-15
Var. menisculus et var. upsaliensis quoad structuras item ad instar similis sed distinguenda individuis semper valde minoribus, striis et lineolis densius positis. Valvae late lanceolatae apicibus (modice) obtuse rotundatis (sicut alterae varietates) sed longitudo 11-25 (usque ad 30?) um, latitudo circiter 6-7.5 um. Striae transapicales 10.5-15 in 10 um, lineolae cirticer 28-32 in 10 um.
Lange-Bertalot, H. and Metzeltin, D. (1996). Indicators of oligotrophy - 800 taxa representative of three ecologically distinct lake types, Carbonate buffered - Oligodystrophic - Weakly buffered soft water. Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 2. Ecology, Diversity, Taxonomy. Koeltz Scientific Books. Königstein, Germany, 2:390 pp.
Rumrich, U., Lange-Bertalot, H. and Rumrich, M. (2000). Diatoms of the Andes. From Venezuela to Patagonia/Tierra del Fuego and two additional contributions. Lange-Bertalot, H. (ed.), Iconographia Diatomologica. Annotated Diatom Micrographs. Vol. 9. Phytogeography-Diversity-Taxonomy. Koeltz Scientific Books, Königstein, Germany, 9:673 pp.
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.