Staurosirella leptostauron

(Ehrenberg) Williams and Round 1987      Category: Araphid
BASIONYM: Biblarium leptostauron Ehrenberg 1854
SYNONYM(S): Fragilaria leptostauron (Ehrenberg) Hustedt 

Staurosira construens var. venter

 

Staurosirella leptostauron var. dubia
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LM scalebar = 10 µm = 80 pixels.

Observations

Contributor: Eduardo Morales - October 2010
Length Range: 7-33 µm
Width Range: 7-19 µm
Striae in 10 µm: 5-11

Description

Valves are cruciform, 7-19 µm wide and 7-33 µm long. Valves with rounded ends. The central area is broad. 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 the mantle is parallel to the valve face/mantle junction. In girdle view, frustules are rectangular. Cells form ribbon-like colonies, joined by linking spines. A cell within a colony is attached to the substratum by a mucilage pad, or cells may be planktonic. The axial area is linear to lanceolate. Striae are distinct, composed of lineolae. Lineolae are greatest in length midway between the sternum and valve mantle, 5-11 in 10 µm. Lineolae bear finely branched volae and may possess siliceous bridges between lineolae. Striae are parallel in the central area, becoming radiate near the valve ends. Striae extend onto the valve mantle. Costae are not as broad as the striae. Spines are flat, spatulate toward their ends and solid. Spines are present along the valve face edge, except at the apices, and are located on the costae between striae. Well-developed, ocellulimbus type, apical pore fields with round poroids are present. Pore fields are located at the junction between the valve face/mantle. Rimoportulae are absent. Copulae, or girdle bands, are closed and do not bear perforations. Valvocopulae are wider than other girdle elements and bear fimbriae (finger-like projections).

Original Description

Basionym: Biblarium leptostauron
Author: Ehrenberg 1854
Length Range: µm
Striae in 10 µm:

Original Description

Original Images

Cite This Page:
Morales, E. (2010). Staurosirella leptostauron. In Diatoms of the United States. Retrieved May 23, 2013, from http://westerndiatoms.colorado.edu/taxa/species/staurosirella_leptostauron

Species: Staurosirella leptostauron

Contributor: Eduardo Morales

Reviewer: Sarah Spaulding

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Image Credit: Eduardo Morales

  1. Valves cruciform
  2. Striae wide
  3. Spines positioned on costae

Valves of S. leptostauron are cruciform with rounded ends. Striae are wide, formed by lineolate striae. Costae are narrower than striae. Spines are flat near the base, and spatulate toward the ends. Spines are solid and positioned on the costae. Two distinct porefields are present at each apex. Girdle bands are closed and lack perforations; the valvocopulum (first girdle band) is wider than other girdle elements and bears fimbriae.

Compare

Staurosira construens possesses cruciform valves, but differs from Staurosirella leptostauron in having narrower striae, costae wider than striae, hollow spines, and open girdle bands.

Staurosira construens

Citations

Williams, D.M. and Round, F.E. (1987). Revision of the genus Fragilaria. Diatom Research 2: 267-288.

Links & ID's

Index Nominum Algarum (INA)

Transfer INA

California Academy of Sciences (CAS)

Staurosirella leptostauron CAS

North American Diatom Ecological Database (NADED)

NADED ID: 175001

Autecology Discussion

Cells are attached by mucilage pads to substrates and joined in colonies by linking spines.

Habits

Size Range

11-100 µm3 (ie Achnanthidium)

Motility

non motile

Attachment

Habitat

benthic
planktonic

Colony

solitary
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

Staurosirella leptostauron

Distribution

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

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

Staurosirella leptostauron

Responses

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