Navicula symmetrica

Patrick 1944      Category: Symmetrical biraphid
BASIONYM: Navicula symmetrica Patrick 1944

Navicula supleeorum

 

Navicula trilatera
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LM scalebar = 10 µm = 80 pixels.

Observations

Contributor: Kalina Manoylov | Paul Hamilton - June 2010
Length Range: 24-34.5 µm
Width Range: 5-6.5 µm
Striae in 10 µm: 12-17

Description

Valves are linear-elliptical to linear-lanceolate with narrow, rounded apices. Valves are 24.0-34.5 µm long and 5.0-6.5 µm wide. Striae are 12-17 in 10 µm. The axial area is narrow and linear and the central area is asymmetrically rounded. The raphe is filiform with enlarged proximal raphe ends that weakly unilaterally deflected. The distal raphe fissures are distinctly deflected from the valve face onto the mantle, with the deflection to the secondary side. The lineolate striae are strongly radiate at the center and radiate throughout the valve. The space between each stria is equal or wider to the width of the stria. Voigt faults are often evident on the secondary side of the valve. Areolae are 24-28 in 10 µm. A thickened central nodule is present on the primary side, positioned between the deflected proximal fissures.

Original Description

Basionym: Navicula symmetrica
Author: Patrick 1944
Length Range: 33 µm
Width Range: 6 µm
Striae in 10 µm: 15-17

Original Description

Valva linearis vel lanceolata, 33 µ longa, 6µ lata, apicibus rotundatis: striis lineatis 15-17 per 10 µ, ad centrum valvae conspicue radiatis, ad margines valvae minus conspicuae radiatis; area axiali angusta; area centrali distincte rectangulare. In the general shape of the central area and the formation of the striae this species is quite similar to Navicula gracilis Ehr. and its varieties. However, it is typically smaller in size and the striae are more radiate in the center of the valve and radiate instead of convergent at the ends. Also the striae are finer (Fig. 6). Distribution-Brazil: Rio Grande do Sul, current water at roadside, near the Lagua dos Quadros, 385 H. Kleerekoper July: 1941 (A-25741). Type (A-25740), scrapings of stones in a rapid of the river Maquuine, an affluent of the Lagua dos Quadros 337 H. Kleerekoper June 1941 (A-25737).

Original Images

Cite This Page:
Manoylov, K., and Hamilton, P. (2010). Navicula symmetrica. In Diatoms of the United States. Retrieved May 25, 2013, from http://westerndiatoms.colorado.edu/taxa/species/navicula_symmetrica

Species: Navicula symmetrica

Contributor: Kalina Manoylov | Paul Hamilton

Reviewer: Sarah Spaulding

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  1. Valves linear with narrow, rounded apices
  2. Central area asymmetrically rounded
  3. Striae fine, 12-17 in 10 µm

Valves are relatively small and linear with narrow, rounded apices. The central area is asymmetrically rounded. Striae are fine and number 12-17 in 10 µm.

Compare

Navicula symmetrica is smaller than N. escambia. The central area of N. symmetrica is also smaller and more irregular than that of N. escambia. Stria density is higher in N. symmetrica (12-17 in 10 µm) than N. escambia (10-13 in 10 µm). The two species also differ in the number of lineolae per stria at 24-28 and 20-23 in 10 µm, respectively.

Navicula escambia

Citations

Patrick, R.M. (1944). Estudo Limnologico e Biologico das Lagoas da regiao Litoranea Sul- Riograndense II. Some New Diatoms from the Lagoa dos Quadros. Boletin de Museo Naciona, Nova serie, Botanica. 2:6 pp., 9 fig.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Navicula symmetrica CAS

North American Diatom Ecological Database (NADED)

NADED ID:

Autecology Discussion

Habits

Size Range

1001-10,000 µm3 (ie Diatoma vulgaris)

Motility

moderately motile (e.g. Navicula tripunctata)

Attachment

unattached

Habitat

benthic

Colony

solitary

EMAP Assessment

Sampling for 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). Streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming). Over 1200 sites on 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

Navicula symmetrica

Distribution

The distribution map represents the relative abundance of this Navicula symmetrica in the western EMAP study. Relative abundance is a measure of the proportion of cells of this species based on a "fixed count" of 300 total diatom cells counted and identified. Each of the western EMAP sample sites is shown, either with a black dot for sites where Navicula symmetrica was not recorded, or with a red circle indicating the relative abundance of Navicula symmetrica.

Note that the size of the proportional symbols varies between species to help show both abundant and rare species.

Scale for the map to the left

EMAP Response Plots

Navicula symmetrica

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Navicula symmetrica from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.

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.