• Category
  • Length Range
    10-20 µm
  • Width Range
    5-10 µm
  • Striae in 10 µm
    26-30 in raphe valve, 14-18 in rapheless valve
  • Synonyms
    Achnanthes lanceolata var. oestrupii A.Cleve
    Planothidium oestrupii (A.Cleve) Edlund



Valves are elliptic to elliptic-lanceolate, with rounded valve margins and slightly apiculate apices. The raphe valve has a narrow linear axial area, slightly widening in the central part of the valve. The central area is bow-tie-shaped central. The raphe is straight and filiform. The external proximal raphe ends are straight. The striae on the raphe valve are uniseriate and strongly radiate. Short and long striae alternate around the central area The rapheless valve has a variable axial area, from narrow to wide and lanceolate in shape. The axial area is bordered by biseriate striae. The rapheless valve has a wide cavum.


This taxon is rare in occurrence, but has been documented in rivers of the western US (EPA Western EMAP) and in lake sediments of the northeast (EPA NLA 2017). The specimens illustrated on this page were found in the North Umpqua River, Oregon and the Little Kijik River, Alaska.

This species was originally found in Denmark, Sweden and Finland.

Original Description

A. lanceolata v. Østrupii n. var. Fig. 1. Die Form ist von ØSTRUP als »sicher ..... eine Variante von Achn. lanceolata» beschrieben und abgebildet worden (1899 p. 52, Taf. 2 Fig. 14). Sie wurde in Hollerup-Schichten mit Ancylus-Rhoicospheniaflora in Gesellschaft von Navicula toulaae v. danica, N. hungarica v. lüneburgensis u. a. entdeckt. Entsprechend fand ich sie 1920 in alten Wenerseeschichten mit Nav. torneensis, N. hungarica v. lüneburgensis u. a. Diese ausgezeichnete Varietät ist also bisher aufgespürt worden in Dänemark, Westschweden und Mittelfinnland, überall fossil und in etwas halophil betonter Süsswasserassoziation.

  • Basionym
    Achnanthes lanceolata var. østrupii
  • Author
    A.Cleve 1922

Original Images

Ploestrupii  Orig Ill
Ploestrupii  Orig Descr

Cite This Page

Potapova, M. (2019). Skabitschewskia oestrupii. In Diatoms of North America. Retrieved May 30, 2024, from https://diatoms.org/species/skabitschewskia_oestrupii


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