• Category
  • Length Range
    24-50 µm
  • Width Range
    6.9-8.5 µm
  • Striae in 10 µm
    9-12 at the valve center, 14-18 near the apices

Identification

Description

Valves are lanceolate with narrow subapiculate apices and slightly asymmetric to the apical axis. A pore field is present at the footpole. The axial area is narrow and linear, widening to merge with a moderately large elliptic central area. The raphe is straight and weakly lateral, becoming filiform at the proximal and distal ends. Proximal raphe ends are weakly expanded. Distal raphe fissures are hooked to the side opposite the central stigma. Striae are radiate, more strongly so at the footpole but nearly parallel at the headpole. A single stigma lies at the end of the longest central stria. Striae at the center are more widely spaced than striae near the poles. Areolae are fine and number 30-35 in 10 µm.

Autecology

Gomphonema johnsonii is known only from the type locality, a spring on the Willamette National Forest in Oregon.

Original Description

Valves lanceolate with narrow subrostrate apices. Valve length 24–50 μm; valve width 6.9–8.5 μm. Pore field present at the footpole. Valves somewhat asymmetric about the apical axis. Axial area narrow and linear, widening to merge with a moderately large elliptic central area. Raphe straight and weakly lateral, becoming filiform at the proximal and distal ends. Proximal raphe ends weakly expanded; terminal raphe fissures hooked to the side opposite the central stigma. Striae strongly radiate, 9–12 in 10 μm at the valve center, 14–18 in 10 μm near the apices. Areolae 30–35 in 10 μm. One stigma present at the end of the longest central stria.

  • Author
    L.L.Bahls 2013
  • Length Range
    24-50 µm
  • Width
    6.9-8.5 µm
  • Striae in 10µm
    9-12 at valve center, 14-18 near the apices

Original Images

Gomphonemajohnsonii Origimag001
Gomphonemajohnsonii Origdesc017

Cite This Page

Bahls, L. (2013). Gomphonema johnsonii. In Diatoms of North America. Retrieved July 23, 2018, from https://diatoms.org/species/gomphonema_johnsonii

Responses

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