Lange-Bertalot and Hofmann 1993 Category: Symmetrical biraphid
BASIONYM: Navicula cryptofallax Lange-Bertalot and Hofmann in Lange-Bertalot 1993
Contributor: Loren Bahls - December 2011
Length Range: 25-33 µm
Width Range: 5.8-7.2 µm
Striae in 10 µm: 14-16
Valves are lanceolate with narrow rostrate to subcapitate ends. The raphe is filiform, ending in weakly expanded proximal pores that are relatively distant from one another. The axial area is narrow, widening slightly towards the central area. The central area is small and variable in shape with irregular margins. Striae are strongly radiate near the valve center, becoming parallel at the prominent Voigt discontinuities, and finally weakly convergent at the ends. Areolae in the striae are fine and difficult to resolve in LM, numbering about 30 in 10 microns.
Basionym: Navicula cryptofallax
Author: Lange-Bertalot and Hofmann in Lange-Bertalot 1993
Length Range: 23-30 µm
Width Range: 5.5-6.0 µm
Striae in 10 µm: 12-14
Valve stricte lanceolatae apicibus subcapitato-rostratiforme protractis, 23-30 microns longae, 5.5-6 microns latae, i.e. paulo variabiles quoad latitudinem. Raphe filiformis poris centralibus satis distantibus positis inter se; pori indecori visu, exigui, angusti etiam in REM numquam hamati nec declinati. Area axialis angusta parum dilatata ad mediam valvae versus. Area centralis modice parva plusminusve rotundata apparens. Striae transapicales valde radiantes, parallelae sub apices, 12-14 in 10 microns. Lineolae circiter 30 in 10 microns sed difficulter separandae (in LM). REM: Sternum parum elevatum super planitie externa valvae.
Lange-Bertalot, H. (1993). 85 Neue taxa und uber 100 weitere neu definierte Taxa erganzend zur Subwasserflora von Mittleuropa. Bibliotheca Diatomologica 27, 454 p. Cramer, Berlin, Stuttgart.
Lange-Bertalot, H. (2001). Navicula sensu stricto, 10 genera separated from Navicula sensu lato, Frustulia. Diatoms of Europe 2: 1-526.
There are 38 records of Navicula cryptofallax in the Montana Diatom Collection, most of them from flowing waters in the Northern Rocky Mountains, but also from standing waters. Here it prefers weakly alkaline water (mean pH = 7.9) of moderate conductivity (mean SC = 523 µS/cm). Common diatom associates of Navicula cryptofallax are Amphora tumida, Diploneis parma, Encyonopsis perborealis, Encyonema elginense, Cymbopleura subaequalis, Caloneis schumanniana, and Cymbopleura subcuspidata..
The Gallatin River near Bozeman, Montana: home of Navicula cryptofallax.
Credit/Source: Loren Bahls
Abundance-weighted means of selected water quality variables measured concurrently with the collection of samples containing Navicula cryptofallax.
Credit/Source: Montana Diatom Database
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). Over 1200 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.