• Category
  • Length Range
    9.7-21.2 µm
  • Width Range
    7.1-10.4 µm
  • Striae in 10 µm
  • Synonyms
    Achnanthes calcar Cleve 1891
    Planothidium calcar Edlund in Edlund, Soninkhishig, Williams and Stoermer 2001



Valves are elliptic, although they may be slightly constricted in the center. The axial area is narrow and linear on the raphe valve; the axial area is narrow and rhomboid on the rapheless valve. The central area on both valves is asymmetric, expanded to valve margins and contains a cavum. The raphe is straight with sigmoid terminal fissures. The striae are fine, uniseriate and radiate throughout both valves.


Original Description

A. Calcar Cl. - Upper valve broadly elliptic, 0,012 m. m. in length and 0,009 m. m. in breadth, with about 24 striae in 0,01 m. m. It carries on the one side a horseshoe-like thickening, which is prolonged on the other half of the valve into a spur-like projection. The lower valve is not known with certainty, but in the same gathering, in which this species has been found, occurs a valve of similar outline and size, the striæ of which reach the raphe and are 25 in 0,01 m. m. That valve, which has a greta resemblance to Diadesmis lucidula Grun. (V. H. XIV, 40) may possibly be the lower valve of A. Calcar. Pl. III, fig. 8, (9 ?). Ab. 45, 47.

  • Basionym
    Achnanthes calcar
  • Author
    Cleve 1891
  • Length Range
    12 µm
  • Width
    9 µm
  • Striae in 10µm

Original Images

Plcalcar  Orig Ill
Plcalcar  Orig Descr


Apr 06, 2016 - Transfer from Planothidium

The taxon, Planothidium calcar Edlund in Edlund, Soninkhishig, Williams and Stoermer 2001 appeared on this page. (Note that the citation missed attribution to Cleve). As of this date, the name and authorshop is shown as Gliwiczia calcar (Cleve) Kulikovskiy, Lange-Bertalot and Witkowski. - S. Spaulding

Cite This Page

Potapova, M. (2011). Gliwiczia calcar. In Diatoms of North America. Retrieved May 24, 2024, from https://diatoms.org/species/gliwiczia_calcar


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