• Category
  • Length Range
    40-53 µm
  • Width Range
    13-15 (as measured at the broadest portion of the valve) µm
  • Striae in 10 µm



Valves are acuminate-apiculate, asymmetric to the transapical axis, with a rounded footpole. The axial area is straight, broadening transversely to form the central area. The raphe is lateral and undulate. The striae are punctate, radiate at the poles to nearly parallel in the middle of the valve. Striae in the central valve are more widely spaced than other striae. On one side of the central area a stria is shortened, on the other side the central stria terminates next to the single stigma.


Original Description

  • Author
    Ehrenb. 1854

Cite This Page

Kociolek, P. (2011). Gomphonema apicatum. In Diatoms of North America. Retrieved February 24, 2024, from https://diatoms.org/species/gomphonema_apicatum


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