Gomphoneis eriense var. variabilis

Kociolek and Stoermer 1988      Category: Asymmetrical biraphid
BASIONYM: Gomphoneis eriense var. variabilis Kociolek and Stoermer 1988

Gomphoneis eriense var. apiculata

 

Gomphoneis herculeana
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LM scalebar = 10 µm = 80 pixels.

Observations

Contributor: Pat Kociolek - February 2011
Length Range: 25-45 µm
Width Range: 9.5-12 µm
Striae in 10 µm: 10-13 in the center, 14-16 at the poles

Description

Valves are lanceolate-clavate, with a distinctly protracted, broadly rounded head-pole, a robust to linear central portion of the valve and a distinctly rounded footpole. Smaller valves are elliptical-clavate, with the headpole protracted slightly. Striae are radiate at the central portion of the valve and strongly radiate at the poles. The raphe is undulate and lateral. The axial area is narrow, widening slightly towards the central area. A small, barely circular central area with a single stigma is present. The striae have individual areolae observable with DIC or oblique light in the light microscope. Longitudinal lines are distinct near the axial area, less so at the apices. Apical pore fields are present at the footpole.

Gomphoneis eriense var. variabilis is widely distributed throughout western North America.

Original Description

Basionym: Gomphoneis eriense var. variabilis
Author: Kociolek and Stoermer 1988
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Kociolek, P. (2011). Gomphoneis eriense. In Diatoms of the United States. Retrieved September 26, 2016, from http://westerndiatoms.colorado.edu/taxa/species/gomphoneis_variabilis

Species: Gomphoneis eriense

Contributor: Pat Kociolek

Reviewer: Sam Rushforth

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Image Credit: Pat Kociolek

  1. Valves lanceolate-clavate
  2. Longitudinal lines distinct near the axial area
  3. Striae 10-13 in the center valve, 14-16 at the poles

Valves are lanceolate-clavate. Smaller valves are elliptical-clavate, with the headpole protracted slightly. Striae are radiate at the central portion of the valve and strongly radiate at the poles. A small, barely circular central area with a single stigma is present. Longitudinal lines are distinct near the axial area, less so at the apices.

Compare

Gomphoneis eriense var. variabilis is distinguished from other taxa considered within the basionym for this taxon. It differs from G. eriense var. angularis and G. eriense var. rostrata in that the valves are more rounded and have the broadest portion of the valve at the center. Gomphoneis eriense var. variabilis is distinguished from G. subherculeana by being narrower, and having finer striae. Gomphoneis eriense var. variabilis is distinguished from G. septa by smaller valves that are more broadly rounded.

This species has been confused with taxa in Gomphonema, specifically G. ventricosum and G. manubrium. Unlike those species, Gomphoneis eriense var. variabilis has longitudinal lines and striae composed of doubly-punctate striae.

Gomphoneis eriense var. angularis

Gomphoneis septa

Gomphoneis subherculeana

Kociolek & Stoermer

Gomphonema manubrium

Fricke

Citations

Kociolek, J.P. and Stoermer, E.F. (1988). Taxonomy, ultrastructure and distribution of Gomphoneis herculeana, G. eriense and closely related species (Naviculales: Gomphonemataceae). Proc. Acad. Nat. Sci. Phil. 140: 24-97. http://www.jstor.org/stable/4064935

Links & ID's

Index Nominum Algarum (INA)

California Academy of Sciences (CAS)

Gomphoneis eriense var. variabilis CAS

North American Diatom Ecological Database (NADED)

NADED ID: 36002

Autecology Discussion

Habits

Size Range

1001-10,000 µm3 (ie Diatoma vulgaris)

Motility

moderately motile (e.g. Navicula tripunctata)

Attachment

vertical (e.g. stalks)

Habitat

Colony

colonies common

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

Gomphoneis eriense var. variabilis

Distribution

The distribution map represents the relative abundance of this Gomphoneis eriense var. variabilis 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 Gomphoneis eriense var. variabilis was not recorded, or with a red circle indicating the relative abundance of Gomphoneis eriense var. variabilis.

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

Gomphoneis eriense var. variabilis

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Gomphoneis eriense var. variabilis 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.