• Category
  • Length Range
    55-103 µm
  • Width Range
    8.5-10.5 at center; 8.6-12.4 at maximum µm
  • Striae in 10 µm
  • Synonyms
    Fragilaria ulna var. goulardi (Bréb.) Lange-Bert. 1980
  • Genus Considered



Valves are linear-lanceolate with a distinctly constricted mid-valve. The apices are rostrate to subcapitate, and apiculate. The axial area is linear and very narrow. The central area is large, circular, and sometimes asymmetric. Smaller specimens may have short marginal striae in the center valve. Striae are parallel, becoming slightly radiate at the apices. Ghost striae are present in the central area, although they are more visible in larger specimens. Each valve has two rimoportula, with a rimoportula positioned at each apex.


Original Description

S. Goulardi Brébisson in litteris. Schaalen in der Mitte etwas verengt, an den Enden zugespitzt, 0,057-0,080 mm. breit, in der Mitte 0,008 mm., Querstreifen 10 1/2 in 0,01 mm., an den Enden schwach radial in der Mitte auf einem fast quadratischen Raume sehr matt (bei schwacher Vergrösserung fehlend). Buenos Ayres, Portorico, Kamtschatka, Jenissey. Taf. VI, Fig. 119 200/1.

  • Author
    Bréb. ex Cleve and Grunow 1880
  • Length Range
    57-80 µm
  • Width
    9, 8 in the middle µm
  • Striae in 10µm

Original Images

Screen Shot 2015 08 14 At 2 07 32  Pm
Screen Shot 2015 08 14 At 2 11 54  Pm

EMAP Assessment

EMAP Distribution

Synedra Goulardi  Br Bisson 3
Map 3

Response Plots

Synedra Goulardi  Br Bisson

Cite This Page

Bishop, I. (2015). Synedra goulardii. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/synedra_goulardi


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