• Category
  • Diameter
    4-15 µm
  • Width Range
    4-7 µm
  • Striae in 10 µm
    15-22
  • Reported As
    Aulacoseira distans var. septentrionalis (Camburn & Charles 2000)

Identification

Description

Frustules are cylindrical and 4-15 µm in diameter, with a mantle height of 4-7 µm. The ratio of the mantle height to valve diameter is less than 1. The mantle has convex sides and the valve face is flat. Rows of pervalvar areolae are curved to the right (dextrorse) and number 15-22 in 10 µm. The valve face is unornamented except for one row of marginal areolae. Spines are located at the end of each pervalvar costa. Spines are thin and have an 'anchor' shape at the end. The ringleiste is small.

Some valves of A. alpigena have almost straight rows of mantle areolae that also may be almost parallel to the pervalvar axis. Such specimens have been often misidentified as A. distans (Ehrenberg) Simonsen. Crawford and Likhoshway (1999) examined the type material of A. distans and showed that it is characterized by numerous rimportulae that internally form short tubes, situated close to a very deep ringleiste. These rimportulae are easily observed in LM in valve views. A. alpigena does not have such prominent and numerous rimoportulae and differs from A. distans also by having higher density of mantle areolae, shallow ringleiste, and plain valve face.

Autecology

Oligotraphentic species

Original Description

  • Basionym
    Melosira distans var. alpigena
  • Author
    Grunow in Van Heurck 1882

Original Images

Melosira distans var. alpigena orig illus
Aulacoseira alpigena orig descr

EMAP Assessment

EMAP Distribution

A Alpigena 10
Map 10

Response Plots

Aulacoseira Alpigena

Cite This Page

Potapova, M. (2009). Aulacoseira alpigena. In Diatoms of North America. Retrieved July 20, 2018, from https://diatoms.org/species/aulacoseira_alpigena

Responses

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