Kociolek and Stoermer 1991 Category: Asymmetrical biraphid
BASIONYM: Gomphonema pygmaeum Kociolek and Stoermer 1991
Contributor: Pat Kociolek - September 2015
Length Range: 10-40 µm
Width Range: 3-5 µm
Striae in 10 µm: 10-13 in the center, 14-16 at the footpole
Valves are linear-clavate, with a squarish to rounded, protracted headpole. The footpole is rounded. The axial area is narrow, and expanded to form a transverse fascia as a central area. Striae are shortened on either side of the central area. A single, distinct stigma is present near the proximal raphe ends. The raphe is weakly lateral and slightly undulate. The external proximal ends are slightly dilated and rounded. Striae are radiate, near the center, becoming more strongly radiate at the footpole.
Under SEM, G. pygmaeum has C-shaped areolae and a round, unoccluded opening of the stigma. The proximal fissures of the raphe are dilated, while the distal raphe ends are deflected onto the mantle. The apical porefield is bisected by the raphe and formed by round, unoccluded porelli that are separated from the areolae by a hyaline area.
Basionym: Gomphonema pygmaeum
Author: Kociolek and Stoermer 1991
Length Range: 11-40 µm
Width Range: 3-5 µm
Striae in 10 µm: 11-13
Kociolek, J.P. and Stoermer, E.F. (1991). Taxonomy and ultrastructure of some Gomphonema and Gomphoneis taxa from the Upper Laurentian Great Lakes. Canadian Journal of Botany 69: 1557-1576. 10.1139/b91-200
Gomphonema pygmaeum was described from rock scrapes from the shore of Lake Superior. The specimens illustrated here are from Oregon, and it likely occurs in other regions of the country.
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.