• Category
  • Length Range
    21-32 µm
  • Width Range
    3.6-4.8 µm
  • Striae in 10 µm



Valves are linear, with slightly triundulate margins. The apices are rounded and slightly set-off. The raphe is lateral. The axial area is narrow and linear. The central area is elliptic and apically elongated. The striae are parallel to weakly radiate in the valve center, becoming slightly convergent at the apices.


This taxon is a cold-water species. It is common in the Arctic, but its geographic range is not well understood because of the past confusion of this species with C. tenuis. Specimens shown on this page are from a sample from a sphagnum swamp in Anchorage, Alaska, with a pH 6.2 (Foged 1981).

Original Description

Valvae lineares cum leniter triundulatis marginibus et descrescentibus rotundatis apicibus. Longitudo 18-32 µm, latitudo 3.0-4.5 µm, cum 20-23 µm striis in 10 µm. Area centralis elliptica confundens cum axiali area. Area axialis angusta, et linearis ad linearem-lanceolatam. Interne, striae alveolatae. In externo visu, striae multiseriales (4 porosae series), leniter radiatae ad parallelas ubique. Striae interruptae ad valvam marginem ante continuans deorsum limbum. Striae non interruptae approximatae ad valvam marginem ante continuans deorsum limbum. Striae non interruptaeapproximatae ad apicem, et striae adsunt in apice. Raphe recta, in LM ramificantis lateralis. Proximales fissurae parvae, lineares ad ellipticas pori situi in expansa area centrali in leniter evolutis centralibus nodulis. Distales fissurae deflectunt ut continui fornices ad unum latum apicis et terminant approximatae ad basim limbi. Interne, distalis fissura format distinctam linearem-ellipticam helictogloassam' centrales fissurae simplices pori ut deflectari aut non deflectari. Interne, aperientes ad alveolam marginalem et maiores quam 1/2 et minas quam 2/3 longitudo striarum. Costae parcae inter strias leniter elevatae ex frond. Copulae apertae taenia, aliquae cum seriebus ellipticorum pororum in parte exteriore, diversae sine structuris.

  • Author
    P.B.Hamilton and D.Anton. 2009
  • Length Range
    18-32 µm
  • Width
    3-4.5 µm
  • Striae in 10µm

Original Images

Caloneis Fusus Orig Ill1
Caloneis Fusus Orig Descr

Cite This Page

Potapova, M. (2020). Caloneis fusus. In Diatoms of North America. Retrieved September 26, 2022, from https://diatoms.org/species/caloneis-fusus


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