• Category
  • Diameter
    4-11 µm
  • Width Range
    4-19 µm
  • Striae in 10 µm



Frustules are cylindrical and form short chains. The ratio of the mantle height to valve diameter is close to 1. The mantle has straight sides, but the mantle/valve face junction is rounded. The valve face appears slightly convex in LM, but flat in SEM. Rows of pervalvar areolae are straight, parallel to the pervalvar axis, 22-31 in 10 µm, with 30-42 areolae in 10 μm. The height of the collum is approximately1/2-1/3 of the mantle height. The valve face is plain, but with short radial striae at the periphery. The spines are anchor-shaped, narrow, and originate from every second or third costa. The ringleiste is shallow and bell-shaped in cross-section.

Original Description

Frustules rectangular in girdle view, valves slightly rounded at the mantle. Valve (5.0) 6.9-11.0 μm in diameter. Pervalvar axis variable in length, (4.0) 7.0-17.0 (19.0) μm. Valve mantle contains striae which are parallel to the pervalvar axis, striae 20-22 in 10 μm. Striae are finely punctate, puncta 25-30 in 10 μm. Sulcus well developed. Periphery of valve face ornamented with a narrow (<1.0 μm) band of radiate striae. Striae ca. 30 in 10 μm. The remaining valve face is unornamented. A row of spines occurs around the circumference of the valve face, a spine is located every 2-3 striae. Spines ca. 1.0-1.5 μm in length

  • Basionym
    Melosira nygaardii
  • Author
    Camburn in Camburn and Kingston 1986
  • Length Range
    5-11 µm
  • Width
    4-19 µm
  • Striae in 10µm

Original Images

Orig Ill  Aunyg
Orig Descr  Aunyg 2
Original text and images reproduced with permission by Academy of Natural Sciences of Philadelphia.

Cite This Page

Potapova, M., English, J. (2010). Aulacoseira nygaardii. In Diatoms of North America. Retrieved May 29, 2024, from https://diatoms.org/species/aulacoseira_nygaardii


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