Navicula rostellata

Kützing 1844      Category: Symmetrical biraphid
BASIONYM: Navicula rostellata Kützing 1844
SYNONYM(S): Navicula viridula var. rostellata (Kützing) Cleve 

Navicula rhynchotella

 

Navicula salinarum
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LM scalebar = 10 µm = 80 pixels.

Observations

Contributor: Marina Potapova | Pat Kociolek - March 2011
Length Range: 32-41 µm
Width Range: 8.0-9.1 µm
Striae in 10 µm: 12-14

Description

Valves are linear to linear-lanceolate with slightly convex (more typically) to straight margins and subrostrate apices. The axial area is narrow and straight. The central area is elliptic and slightly asymmetric. The raphe is straight, with external proximal raphe ends that are slightly dilated and bent toward the primary side of the valve. The central nodule is asymmetrically expanded on the internal valve surface to the primary side. Terminal raphe fissures are hooked to the secondary valve side. Striae are bent and radiate around the center. The striae are more distant from one another near the center of the valve, 12-14 in 10 µm. The striae become parallel, then convergent at the apices. The areolae are usually visible under LM and number around 30 in 10 μm.

Note that the original material of Navicula rostellata has not been investigated. As Patrick (Patrick & Reimer 1966) pointed out, the identity of this taxon is not clear as the original illustration shows a linear valve outline and long, narrow apices. Patrick and Reimer (1966) illustrated a specimen from Bengal with linear valve outline and low striae density (9-10 striae in 10 µm) as N. viridula var. rostellata. The concept we present in this page follows Lange-Bertalot (2001).

Original Description

Basionym: Navicula rostellata
Author: Kützing 1844
Length Range: 25-38 µm
Striae in 10 µm:

Original Description

N. minuta, striata, oblonga, lateribus parallelis, apicibus rostratis elongates acutis. Long. 1/90-1/60’’’.

Original Images

Cite This Page:
Potapova, M., and Kociolek, P. (2011). Navicula rostellata. In Diatoms of the United States. Retrieved June 19, 2013, from http://westerndiatoms.colorado.edu/taxa/species/navicula_rostellata

Species: Navicula rostellata

Contributor: Marina Potapova | Pat Kociolek

Reviewer: Rex Lowe

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Image Credit: Marina Potapova

  1. Valves linear to linear-lanceolate with subrostrate apices
  2. Proximal raphe ends bent
  3. Central nodule expanded to primary side
  4. Central striae radiate, bent
  5. Areolae ~ 30 in 10 μm

Valves are linear to linear-lanceolate with subrostrate apices. The central area is often slightly asymmetrical. The raphe is straight, with external proximal raphe ends slightly dilated and bent towards primary side of the valve. The central nodule is asymmetrically expanded on the internal valve surface to the primary side. Striae are radiate and bent around the center, 12-14 in 10 µm, becoming parallel, then convergent at the apices.

Compare

Navicula rostellata differs from N. germainii by linear-lanceolate and on average slightly wider valves. The areolae are more clearly visible under LM in N. rostellata than in N. germainii. Navicula subrhynchocephala can be distinguished by proximal raphe ends hooked to the secondary valve side, almost symmetric central nodule, straight striae in the valve center, and lower areola density (24-25 in 10 μm compared to 30 in 10 μm in N. rostellata).

Navicula germainii

Navicula subrhynchocephala

Citations

Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Navicula rostellata CAS

North American Diatom Ecological Database (NADED)

NADED ID: 46616

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 rostellata

Distribution

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

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 rostellata

Responses

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