Valves are linear to linear-lanceolate with rounded apices. The valve margins are straight to slightly convex in smaller specimens. The axial area is linear and expanded at the central valve to form a broad transverse fascia. The fascia is typically asymmetric from one side of the axial area to the other. The raphe is straight and filiform, with dilated proximal external ends. The striae are parallel to radiate. Longitudinal lines are visible in larger specimens.


Original Description

Stauroneis Bacillum nov. spec. Stauroneis minor valvis anguste lineari oblongis apice rotundatis, nodulo centrali magno omnem valvae latitudinem occupante, striis transversis tenuissimis ultra 70 in 0.001". Longit. 0.0010-0.0015", latit. valvae 0.0002— 0.0003". — Tab. nostr. 13 fig. 16 a, b (400/1). Habitat in aqua subsalsa ad litora Angliae prope Newhaven (legi August 1861). Die einzige mir bekannte ähnliche Art ist Stauroneis rectangularis Gregory , die aber durch grössere Gestalt, etwas stumpf vorgezogene Spitzen und viel stärkere Streifung hinreichend verschieden ist.

  • Basionym
    Stauroneis bacillum
  • Author
    Grunow 1863

EMAP Assessment

EMAP Distribution

Caloneis Bacillum 40 Copy
Map 40

Response Plots

Caloneis Bacillum Copy

Cite This Page

Kociolek, P. (2011). Caloneis bacillum. In Diatoms of North America. Retrieved June 19, 2018, from


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