Valves lanceolate-trullate, tapering to a rounded to obtuse headpole, and more abruptly to the rounded footpole. Valves broadest below the central nodule. Striae are radiate, strongly so at the apices, more coarse around the center and more dense at the apices. Striae are biseraite. The axial area is narrow, broadening slightly to form a linear central area. One stigma, sometimes accompanied by a second stigma or isolated punctum, occur in the central area. Raphe is lateral and distinctly undulate. Longitudinal lines are submarginal in larger specimens, positioned about ½ the way between the margin and axial area in smaller specimens. Septa are very large at the headpole. Septa and pseudosepta are present at both poles.


Original Description

  • Author
    Kociolek and Stoermer 1986

Cite This Page

Kociolek, P. (2011). Gomphoneis trullata. In Diatoms of North America. Retrieved July 20, 2018, from


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