Navicula libonensis

Schoeman 1969      Category: Symmetrical biraphid
BASIONYM: Navicula libonensis Schoeman 1970

Navicula leptostriata

 

Navicula longicephala
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LM scalebar = 10 µm = 80 pixels.

Observations

Contributor: Marina Potapova - February 2011
Length Range: 27-35 µm
Width Range: 5.9-7.0 µm
Striae in 10 µm: 12-13

Description

Valves are lanceolate with rounded or very slightly drawn-out ends. The axial area is narrow and linear. The central area is transversely elliptical or irregular-rectangular, often slightly asymmetrical. The proximal raphe ends are straight, slightly expanded. Terminal raphe fissures are hooked towards the secondary side. The lineolate striae are radiate, becoming convergent at the valve apices, 12-13 in 10 µm. The areolae are easily observed under LM, 28-32 in 10 µm.

Note that this concept of Navicula libonenesis follows Lange-Bertalot (2001), but the type material of this species have not been photographed. Therefore it is not clear at present whether North American, European, and South African populations represent the same species.

Original Description

Basionym: Navicula libonensis
Author: Schoeman 1970
Length Range: 24-32 µm
Width Range: 5-7 µm
Striae in 10 µm: 11-14

Original Description

The valves are lanceolate with regularly rounded ends which are not produced, 24-32 μ long and 5-7 μ wide. The raphe is straight and filiform bending sharply near the poles towards the same side of the valvar margin; the terminal fissures were observed in only a few cases and appeared to run alongside the valvar margin, thus bending towards the valvar poles; the central poles are small but definite, fairly close together, The axial area is narrow and linear with definite polar areas, and widens into a central area due to the regular or irregular shortening of the central striae. The transapical striae are radial becoming parallel or convergent near the poles, 11-14 in 10 μ (13-14 in 10 μ near the poles of the valve), clearly lineolate. Lineolae form longitudinal striae, 28-30 in 10 μ.

Original Images

Cite This Page:
Potapova, M. (2011). Navicula libonensis. In Diatoms of the United States. Retrieved May 22, 2013, from http://westerndiatoms.colorado.edu/taxa/species/navicula_libonensis

Species: Navicula libonensis

Contributor: Marina Potapova

Reviewer: Pat Kociolek

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Image Credit: Marina Potapova

  1. Rounded or very slightly protracted ends
  2. Proximal raphe ends straight
  3. Striae radiate at center, becoming convergent at apices
  4. Areolae visible in LM

Valves are lanceolate with rounded or very slightly drawn-out ends. The proximal raphe ends are straight and slightly expanded. The central area is transversely elliptical or irregular-rectangular, often slightly asymmetric. The lineolate striae are radiate, becoming convergent at the valve apices, 12-13 in 10 µm. The areolae are easily observed under LM and number 28-32 in 10 µm.

Compare

Navicula libonensis is similar in size and shape to N. erifuga, but can be distinguished by its straight proximal raphe endings.

Navicula erifuga

Citations

Lange-Bertalot, H. (2001). Navicula sensu stricto, 10 genera separated from Navicula sensu lato, Frustulia. Diatoms of Europe 2: 1-526.

Schoeman, F.R. (1969). Diatoms from the Orange Free State (South Africa) and Lesotho. No. 2. Revista de Biologia 7(1-2):35-74,.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Navicula libonensis CAS

North American Diatom Ecological Database (NADED)

NADED ID: 46542

Autecology Discussion

Habits

Size Range

101-1000 µm3 (ie Amphora veneta)

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 libonensis

Distribution

The distribution map represents the relative abundance of this Navicula libonensis 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 libonensis was not recorded, or with a red circle indicating the relative abundance of Navicula libonensis.

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 libonensis

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Navicula libonensis 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.