Navicula rhynchocephala

Ehrenberg 1844      Category: Symmetrical biraphid
BASIONYM: Navicula rhynchocephala Kützing 1844

Navicula reinhardtii

 

Navicula rhynchotella
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LM scalebar = 10 µm = 80 pixels.

Observations

Contributor: Pat Kociolek - March 2011
Length Range: 48-53 µm
Width Range: 9-10 µm
Striae in 10 µm: 8-9 at the center, 11-12 towards the apices

Description

Valves are lanceolate with elongate-protracted, rounded apices. The axial area is narrow, straight, widening to form an irregularly-rounded to elliptical central area. The central area is formed by shortened striae that are also more widely spaced than elsewhere on the valve. The raphe is lateral, slightly arched, with dilated proximal raphe ends. Striae are distinctly lineolate, radiate around the center, becoming parallel, then convergent at the ends.

Taxonomic note: We present N. rhynchocephala following Lange-Bertalot (2001). The specimen illustrated as N. rhynchocephala in Patrick & Reimer (1966) corresponds to our treatment of N. rhynchotella. The type material of N. rhynchocephala, however, has not been investigated and further work may clarify the original type as designated.

Original Description

Basionym: Navicula rhynchocephala
Author: Kützing 1844
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Kociolek, P. (2011). Navicula rhynchocephala. In Diatoms of the United States. Retrieved May 22, 2013, from http://westerndiatoms.colorado.edu/taxa/species/navicula_rhynchocephala

Species: Navicula rhynchocephala

Contributor: Pat Kociolek

Reviewer: Sarah Spaulding

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Image Credit: Pat Kociolek

  1. Valves lanceolate
  2. Apices elongate-protracted, rounded
  3. Central striae widely spaced
  4. Striae distinctly lineate

Valves are lanceolate with elongate-protracted, rounded apices. The axial area is narrow, straight, widening to form an irregularly-rounded to elliptical central area. The central area formed by shortened striae that are also more widely spaced than elsewhere on the valve. The striae are distinctly lineate, radiate around the center, becoming parallel, then convergent at the ends.

Compare

This species is more linear than N. salinarum and N. rhynchotella and more lanceolate than N. tripunctata and other lineolate species of the genus.

Navicula salinarum

Navicula tripunctata

Navicula rhynchotella

Citations

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

Links & ID's

Index Nominum Algarum (INA)

INA

California Academy of Sciences (CAS)

Navicula rhynchocephala CAS

North American Diatom Ecological Database (NADED)

NADED ID: 46154

Autecology Discussion

Habits

Size Range

1001-10,000 µm3 (ie Diatoma vulgaris)

Motility

moderately motile (e.g. Navicula tripunctata)

Attachment

prostrate (e.g. mucilage pad)

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 rhynchocephala

Distribution

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

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 rhynchocephala

Responses

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