(Østrup) Aboal in Aboal, Alvarez-Cobelas, Cambra and Ector 2003 Category: Monoraphid
BASIONYM: Achnanthes oblongella Østrup 1902
Contributor: Marina Potapova -
Length Range: 6-18 µm
Width Range: 3.7-7 µm
Striae in 10 µm: 9-12 on rapheless valve, 24-30 on raphe valve
Valves are elliptical-lanceolate to linear-elliptical. The raphe valve has a narrow linear axial area and a transversely rectangular or bow tie-shaped central area. The raphe is straight, without terminal fissures. The proximal and distal raphe ends are slightly expanded. The proximal raphe ends curve toward opposite sides internally. Striae on raphe valve are slightly radiate in the valve center and strongly radiate and curved at apices, 24-30 in 10 µm. The areolae openings are small, round. The rapheless valve has a lanceolate axial area. The central area is usually not differentiated from the axial area, but sometimes two middle striae on one side of the valve are more distant from each than other striae. Striae on rapheless valve are broader than those on the raphe valve, punctate, parallel in the center and radiate at apices, 9-12 in 10 µm. Shortened marginal striae are often present. The openings of the areolae are apically elongated, internally areolae open into a shallow chamber.
Basionym: Achnanthes oblongella
Author: Østrup 1902
Length Range: 57 µm
Width Range: 6 µm
Striae in 10 µm: 10 in "epitheca" (rapheless valve)
L. 0,057 mm., B. 0,006 mm. Epitheca: apical area narrow, 10 striae in 0,01 mm., finely transversely lineated. Hypotheca: striæ very fine, slightly curved. Central area narrow. Hypotheca of this small species highly reminds of Navicula Rotœana Grun. var. oblongella Grun. (V. H., Syn. tab. XIV,.fig. 21). But as I have seen both valves in situ, I am quite sure it is an Achnanthes.
Aboal, M., Alvarez-Cobelas, M., Cambra, J. and Ector, L. (2003). Floristic list of non marine diatoms (Bacillariophyceae) of Iberian Peninsula, Balearic Islands, and Canary Islands. Updated taxonomy and bibliography. In: A. Witkowski (ed.), Diatom Monographs. A.R.G. Gantner Verlag K.G., 4: 639 pp.
Østrup, E. (1902). Freshwater Diatoms [in Flora of Koh Chang. Part VII. Contributions to the knowledge of the gulf of Siam.John Schmidt (ed.). Preliminary Rept. Bot., Results Dan. Exped. to Siam (1899-1900)]. Botanisk Tidsskrift 25(1): 28-41.
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.