Donkin 1861 Category: Symmetrical biraphid
BASIONYM: Navicula gregaria Donkin 1861
Contributor: Marina Potapova -
Length Range: 16-35 µm
Width Range: 4.1-7.0 µm
Striae in 10 µm: 14-18 in the center valve
Valves are lanceolate with protracted apices. The axial area is narrow and straight. The central area is asymmetric and elliptical. The raphe is straight, with external proximal raphe ends sharply bent toward primary side of the valve. Striae are slightly radiate around the center, becoming parallel, then convergent at the apices. The areolae are clearly visible under LM, numbering 25-32 in 10 μm.
Note that the concept presented here is broad. Others (Lange-Bertalot 2001) report that two distinct morphologies are present on the original Donkin microslide. There is additional discussion on N. gregaria and N. supergregaria in Lange-Bertalot (2001, pg. 85-86, figs. 8-25).
Basionym: Navicula gregaria
Author: Donkin 1861
Length Range: µm
Striae in 10 µm:
Navicula gregaria, n. sp.-Form on S. V. broadly lanceolate, apiculate; striæ obscure.
Cox, E.J. (1995). Taxonomic studies on the diatom genus Navicula Bory VII. The identity and typification of Navicula gregaria Donkin, N. cryptocephala Kutz. and related taxa. Diatom Research 10: 91-111.
Donkin, A.S. (1861). On the marine Diatomaceae of Northumberland with a description of several new species. Quarterly Journal of Microscopical Science, new series, London 1:1-15.
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.