Staurosira construens var. binodis

(Ehrenberg) Hamilton 1992      Category: Araphid
BASIONYM: Fragilaria binodis Ehrenberg

Staurosira construens

 

Staurosira construens var. venter
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LM scalebar = 10 µm = 80 pixels.

Observations

Contributor: Eduardo Morales - October 2010
Length Range: 7-21 µm
Width Range: 4-6 µm
Striae in 10 µm: 13-16

Description

Valves are biundulate in larger specimens and lanceolate to cruciform in smaller ones, 4-6 µm wide and 7-21 µm long. Valves with rostrate to subcapitate ends. The central margin is constricted in larger specimens or inflated in smaller specimens. The valve face is flat, or slightly undulate due to raised costae. The valve face/mantle junction forms a sharp angle. The abvalvar edge of mantle is parallel to the valve face/mantle junction. In girdle view, frustules are rectangular. Cells form ribbon-like colonies joined by linking spines. One frustule within a colony is attached to the substratum by a mucilage pad. Cells may also be planktonic. The axial area is broad and linear or slightly lanceolate. The striae are distinct, alternate, and composed of lineolae which decrease in size from the valve face/mantle edge to both the central sternum and the valve mantle; 13-16 in 10 µm. Lineolae bear finely branched volae. The striae are parallel to radiate in the central area. Near the valve ends, the striae are slightly radiate to parallel. Striae extend deep onto the valve mantle. Costae are broad. Spines are spatulate, hollow and some possess terminal digitations that attach to neighboring valve lineolae. Spines are present along the valve face edge, except at the apices, and always located on the costae between striae. Well-developed, ocellulimbus type, apical pore fields with round poroids are present. Apical pore fields are located on the valve mantle. Rimoportula are absent. Scab-like structures, or blisters, are present along the abvalvar side of valve mantle. Copulae lack perforations. Valvocopulae wider than copulae.

Original Description

Basionym: Fragilaria binodis
Author: Ehrenberg
Length Range: µm
Striae in 10 µm:

Original Description

Sr. construens, testula minima laevis, angulis productis subaequalibus.

Original Images

Cite This Page:
Morales, E. (2010). Staurosira construens. In Diatoms of the United States. Retrieved May 21, 2013, from http://westerndiatoms.colorado.edu/taxa/species/staurosira_construens_var._binodis

Species: Staurosira construens

Contributor: Eduardo Morales

Reviewer: Sarah Spaulding

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Image Credit: Eduardo Morales

  1. Valves bi-undulate
  2. Axial area linear to lanceolate
  3. Apical pore fields present
  4. Spines hollow

Valves at the larger end of the size range of S. construens var. binodis are bi-undulate, while smaller specimens are lanceolate to cruciform. The axial area is linear to slightly lanceolate. Two apical pore fields are present on the valve mantle. Under the SEM, the apical porefields are found to be composed of round poroids. Spines are hollow, spatulate and located between striae.

Compare

Staurosira construens var. binodis should be compared to Pseudostaurosira robusta, which has a broad axial area and areolae that are wider and restricted to the valve margin.

Pseudostaurosira robusta

(Fusey) Williams & Round

Citations

Ehrenberg, C.G. (1854). Mikrogeologie. Einundvierzig Tafeln mit über viertausend grossentheils colorirten Figuren, Gezeichnet vom Verfasser. Voss, Leipzig., Pl. 5, II, fig. 23 (iconotype).

Ehrenberg, C.G. (1843). Verbreitung und Einfluß des mikroskopischen Lebens in Süd- und Nord-Amerika. Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin, 1841: 291-445, 4 Tafel.

Hamilton, P.B., Poulin, M., Charles, D.F., and Angell, M. (1992). Americanarum Diatomarum Exsiccata: CANA, Voucher Slides from Eight Acidic Lakes in Northeastern North America. Diatom Research 7(1):25-36.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Staurosira construens var. binodis CAS

North American Diatom Ecological Database (NADED)

NADED ID: 172005

Autecology Discussion

Cells form ribbon-like colonies.

Habits

Size Range

11-100 µm3 (ie Achnanthidium)

Motility

non motile

Attachment

vertical (e.g. stalks)

Habitat

benthic
planktonic

Colony

occasional colony

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

Staurosira construens var. binodis

Distribution

The distribution map represents the relative abundance of this Staurosira construens var. binodis 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 Staurosira construens var. binodis was not recorded, or with a red circle indicating the relative abundance of Staurosira construens var. binodis.

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

Staurosira construens var. binodis

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Staurosira construens var. binodis 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.