Valves are linear-clavate with headpole rounded, footpole narrowly rounded. The striae are parallel to radiate, strongly radiate at the footpole and uniseriate. The axial area is narrow at the poles, widening towards the central area. The central area is broadly rectangular with shortened striae on either side; the central striae are more widely spaced than the others. A stigma is located in the central area. The raphe is straight and lateral, with external proximal raphe ends dilated slightly.

Note that the present concept of this species is based on the variation of the type population. This species is either variable in US material, or there are a number of species within the species complex. Specimens with a more narrow axial area or more elongate valve are reported by analysts. Further studies are necessary to establish species limits for this and closely related species.


Original Description

  • Author
    Kociolek and Kingston 1999
  • Length Range
    10.5-30.0 µm
  • Width
    3.5-5.0 µm
  • Striae in 10µm

Original Images

Gomphonema kobayasii orig illus
Gomphonema kobayasii SEM
G Kobayasii Orig Description

EMAP Assessment

EMAP Distribution

Gomphonema Kobayasii 40 Copy
Map 40

Response Plots

Gomphonema Kobayashi Copy 1

Cite This Page

Kociolek, P. (2011). Gomphonema kobayasii. In Diatoms of North America. Retrieved June 21, 2018, from


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