• Category
  • Length Range
    27.3-32.1 µm
  • Width Range
    7.0-7.5 µm
  • Striae in 10 µm



Valves are elliptic-lanceolate, with protracted, rostrate apices. The valve ends are broadly rounded, with prominent polar bars that are recurved into the valve. The axial area and conopeum are linear and narrow. The raphe is filiform and straight. The proximal raphe ends are inflated, while the distal raphe ends are unilaterally deflected. The central area is strongly bow-tie shaped, and bordered by short striae of even length. The central area may be asymmetric, with one side of the "bow-tie" larger than the other. Striae are strongly radiate, becoming convergent at the apices.

This taxon is considered a member of the S. pupula species complex. Prior to the description of S. auldreekie in 2004, it would have been identified as S. pupula. Likely, many of the records in surveys of North America this taxon is recorded as S. pupula.


Due to morphological similarities with Sellpahora pupula, S. auldreekie has not been illustrated from the United States. Here we observed samples from Moody Lake, Minnesota.

Original Description

Valvae ellipticae polis valde rostratis angustis, in medio quam in polis 2-3plo latiores, 15-35 µm longae, 6.6-8 µm latae. Area ax­ialis angusta recta; raphosternum extus non vixve elevatum, fronte igitur plana. Area centralis est subfascia angulis acutis dictu Angliae 'bow-tie' similis. Areolae poroides parvae circulares secus striam c.65 in 10 µm regulatim dispositae. Striae uniseriatae 19-24 in 10 µm pro parte maxima radiantes, in valvis maioribus prope polos convergentibus. Transtra polaria ad axem apicalem perpendicularia. Raphe simplex recta filiformis, extremis centralibus expansis versus latus secundarium fexis.

  • Author
    D.G.Mann and S.M.McDonald 2004
  • Length Range
    15-35 µm
  • Width
    6.6-8 µm
  • Striae in 10µm

Original Images

Seauldreekie Type Image
Seauldreekie Type Text

Cite This Page

Burge, D., Edlund, M. (2017). Sellaphora auldreekie. In Diatoms of North America. Retrieved July 13, 2024, from https://diatoms.org/species/sellaphora_auldreekie


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