Diatoms of North AmericaDiatoms of North America

Staurosirella pinnata

(Ehrenb.) D.M.Williams and Round 1987

Staurosirella Pinnata Guide
  • Category
    Araphid
  • Length Range
    4-10 µm
  • Width Range
    3-4 µm
  • Striae in 10 µm
    11-14

Identification

Staurosirella pinnata LM2 Staurosirella pinnata LM1 Staurosirella pinnata LM3 Staurosirella pinnata LM4 Staurosirella pinnata LM5
View image metadata
Staurosirella pinnata SEM2 Staurosirella pinnata SEM1 Staurosirella pinnata SEM3

Description

Valves are ovoid, 3-4 µm wide and 4-10 µm long with rounded ends. Valve face flat, or slightly undulate due to raised costae. In girdle view, frustules are rectangular and form ribbon-like colonies, joined by linking spines. Colonies are attached to the substratum at one end by a frustule with a a mucilage pad, or colonies may be planktonic. Axial area is linear to lanceolate. Striae are distinct, 11-14 in 10 µm. Lineolae are long, forming wide striae. Striae vary from parallel in the valve center to radiate toward the valve ends. Striae extend onto the valve mantle. Costae are more slender than the striae. Spines are positioned on costae along the valve margin, except at the apices. Spines are conical at the base and spatulate towards the terminus. A single apical pore field with round poroids is present, displaced toward valve mantle. Girdle bands are open and do not bear perforations.

Samples collected from North America exhibit several morphological variants that are often included under the name Staurosirella pinnata. Since the type of this taxon has not been studied in detail, it is difficult to determine which of these variants corresponds to the “true” S. pinnata. We consider the specimens depicted in this page closely resemble the iconotype specimens presented by Ehrenberg (1843).

Autecology

This taxon is widely distributed in freshwater (Patrick and Reimer 1966), and has been reported with light micrographs from lakes in the Northeastern US (Camburn and Charles 2000), northern Québec and Labrador (Fallu et al. 2000), Cape Cod (Siver et al. 2005), the Canadian Arctic Archipelago (Antoniades et al. (2008), the Great Lakes (Reavie and Kireta 2015),

In the Great Lakes National Parks (Edlund et al. 2009, 2011, 2012, 2013), this taxon is common (5-25% abundance) to uncommon (1-5% abundance) in sediment core material from Isle Royale (Ahmik, Richie and Harvey lakes), Pictured Rocks (Grand Sable and Beaver lakes), Voyageurs ( Ek, Peary, Little Trout, and Mukooda lakes), Sleeping Bear Dunes (Manitou and Bass lakes), and the St. Croix Scenic Riverway (Lake St. Croix).

This taxon is reported to be an indicator of moderate environmental stress (Reavie and Kireta 2015).

Many research groups consider this taxon an indicator organism and published regional environmental optima and tolerances including:

Camburn and Charles (2000): pH - 7.15 +/- 0.55, Acid Neutralizing Capacity - 174 +/- 128 µeq/L, Total Aluminum - 36 +/- 42 µg/L, Dissolved Organic Carbon (DOC) - 129 +/- 174 µmol/L, Total Phosphorus (TP) - 11.15 +/- 6.36 µg/L for populations from the Northeastern US.

Fallu et al. (2000): DOC - 5.46 +/- 1.49 mg/L, Color - 18 +/- 2.9 Pt units, Alkalinity - 69 +/- 2.7 µeq/L for populations from northern Québec and Labrador.

Siver et al. (2005): pH - 6.5 +/- 0.7, TP - 14.3 +/- 7 µg/L for populations from Cape Cod.

Antoniades et al. (2008): pH - 7.5, Tolerance Range - 6.8-8.1, Conductivity - 47 µS/cm, Tolerance Range - 16-132 µS/cm, Dissolved Organic Carbon - 1.27 mg/L, Tolerance Range - 0.76-2.12 µS/cm for populations from the Canadian Arctic Archipelago.

Reavie and Kireta (2015): Report this taxon to have a total phosphorus optima just below 30 µg/L and a chlorine optima just below 10 µg/L for populations in the Great Lakes.

Original Description

F. pinnata, lineari-oblonga striis validis in 1/100 lin. 15, apicibus simpliciter rotundatis. Affinis striolatae et syricae. Icon!

  • Basionym
    Fragilaria pinnata
  • Author
    Ehrenb. 1843

Original Images

Staurosirella Pinnata Iconotype
Staurosirella Pinnata Original Description

Citations & Links

Citations

Links

Updates

Feb 11, 2026 - Addition of Autecology

From 2010 to until 2026, the autecological information on this taxon page was limited. As of this update, information on ecology, biogeography, and environmental optima have been added. - Lane Allen and Mark Edlund

Cite This Page

Morales, E., Edlund, M., Allen, L. (2010). Staurosirella pinnata. In Diatoms of North America. Retrieved March 23, 2026, from https://diatoms.org/species/44990/staurosirella_pinnata

Responses

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