Decussata placenta

(Ehrenberg) Lange-Bertalot and Metzeltin in Lange-Bertalot 2000      Category: Symmetrical biraphid
BASIONYM: Navicula placenta Ehrenberg 1854

Cymbopleura subrostrata

 

Denticula tenuis

LM scalebar = 10 µm = 40 pixels.



Observations

Contributor: Pat Kociolek - January 2011
Length Range: 24-50 µm
Width Range: 13-18 µm
Striae in 10 µm: 22-27

Description

Valves are elliptical with rostrate to rostrate-apiculate to capitate-apiculate apices. The axial area is narrow, expanded at the center to form a transapically oval to circular central area. The raphe is filiform, straight to slightly undulate, with prominent, dilated external proximal raphe ends. Areolae from neighboring striae are slightly offset, producing a quincunx pattern; areolae are circular. Striae are arranged in three patterns: radiate and two crossing oblique patterns.

This is a distinctive species. Our observations expand the size range of this taxon beyond that reported by Patrick & Reimer (1966), although the valve apices are typically more capitate-apiculate than the illustrated population (Edlund et al. 2006).



Original Description

Basionym: Navicula placenta
Author: Ehrenberg 1854
Length Range: µm
Striae in 10 µm:

Original Description

Original Images


Cite This Page:
Kociolek, P. (2011). Decussata placenta. In Diatoms of the United States. Retrieved April 18, 2014, from http://westerndiatoms.colorado.edu/taxa/species/decussata_placenta

Species: Decussata placenta

Contributor: Pat Kociolek

Reviewer: Mark Edlund

Citations

Edlund, M.B., Brant, L.A., Levkov, Z. and Nakov, T. (2006). An emended description of Decussata (Patrick) Lange-Bertalot & Metzeltin that includes protoplast organization and detailed valve and cingulum ultrastructure. Diatom Research 21: 269-280.

Krammer, K. and Lange-Bertalot, H. (1986). Bacillariophyceae. 1. Teil: Naviculaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/1. Gustav Fisher Verlag, Jena. 876 pp.

Lange-Bertalot, H. (2000). Transfer to the generic rank of Decussata Patrick as a subgenus of Navicula Bory. Iconographia Diatomologica 9: 670-673.

Patrick, R.M. and Reimer, C.W. (1966). The Diatoms of the United States exclusive of Alaska and Hawaii, V. 1. Monographs of the Academy of Natural Sciences of Philadelphia 13.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Decussata placenta CAS

North American Diatom Ecological Database (NADED)

NADED ID: 219001

Autecology Discussion

Widely distributed, found commonly in aerophilous conditions

EMAP Assessment

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.


EMAP Distribution

Decussata placenta


EMAP Response Plots

Decussata placenta


EMAP citations

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.