(Agardh) Lange-Bertalot 1980 Category: Asymmetrical biraphid
BASIONYM: Gomphonema abbreviatum Agardh 1831
SYNONYM(S): Gomphonema abbreviatum Agardh | Rhoicosphenia curvata (Kützing) Grunow
Contributor: Marina Potapova - May 2009
Length Range: 10–55 µm
Width Range: 4–8 µm
Striae in 10 µm: 15-20
Valves are clavate. with rounded apices. Frustules are heteropolar, appearing bent in girdle view. The ventral valve is concave, with a fully developed raphe system. The dorsal valve is convex, with short raphe slits situated close to the poles. The central area is oval to elliptic. A pseudoseptum is present at both poles on valve margins. Striae are uniseriate. Areolae are apically elongated. Cells occur on stalks, forming colonies.
Basionym: Gomphonema abbreviatum
Author: Agardh 1831
Length Range: µm
Striae in 10 µm:
G. abbreviatum, pedunculo subramoso cymbellis conicis fastigiatis breviore.
Agardh, C.A. (1831). Conspectus Criticus Diatomacearum. Part 3. Lundae. Litteris Berlingianis. pp. 33-48.
Lange-Bertalot, H. (1980). Ein Beitrag zur Revision der Gattungen Rhoicosphenia Grun., Gomphonema C. Ag., Gomphoneis Cl. Botaniska Notiser 133:585-594.
Mann, D.G. (1982). Structure, life history and systematics of Rhoicosphenia (Bacillariophyta) I. The vegetative cell of Rh. curvata. Journal of Phycology 18: 162-176.
Mann, D.G. (1982). Structure, life history and systematics of Rhoicosphenia (Bacillariophyta) II. Auxospore formation and perizonium structure of Rh. curvata. Journal of Phycology 18: 264-274.
Mann, D.G. (1984). Structure, life history and systematics of Rhoicosphenia (Bacillariophyta) V. Initial cell and size reduction in Rh. curvata and description of of the Rhoicospheniaceae fam. nov. Journal of Phycology 20: 544-555.
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.
Investigation of Rhoicosphenia in North America has resulted in recognition of species in addition to R. abbreviata. Previously, the concept presented here was broad and included R. californica. An image of R. californica was removed and the text adjusted to reflect a more narrow concept. A pdf copy of the original species page is available upon request. - S. Spaulding