• Category
  • Length Range
    13.1-25.3 µm
  • Width Range
    4-4.4 µm
  • Striae in 10 µm
    8-9 at mid-valve; 12-15 at the apices

Identification

Description

Valves clavate, with variably broad, rounded headpoles and narrowly rounded footpoles. Striae are radiate and alternate throughout, and increase in density as they approach both apices. The axial area is narrow but expands near the central area. The raphe is either straight or undulate and weakly lateral. The central area is robustly siliceous and distinctly asymmetric due to a single extended middle stria, which reaches from one margin to a single isolated stigma near the apical axis. An apical porefield is present at the footpole.

Note that the largest valve of the holotype population below does not conform to the original description, particularly in reference to a dominant central striae on on side of the central area.

Autecology

This taxon is commonly encountered in stream and lake systems in the northeastern United States. The imaged valves for this page were found in samples collected in wadeable streams in New York, New Hampshire, Massachusettes, and Connecticut.

In their examination of diatoms in low-alkaline Adirondack lakes, Camburn and Charles (2000) found G. variostriatum in only 5 out of 116 lakes examined. The metrics provided in that publication suggests that G. variostriatum has a preference for relatively low pH waters and an intolerance of higher total P and DOC.

Original Description

  • Author
    Camburn and D.F.Charles 2000
  • Length Range
    16-32 µm
  • Width
    3.8-6.0 µm
  • Striae in 10µm
    7-9 at mid-valve, up to 14-15 at the ends

Original Images

Gomphonema variostriatum orig illus
G Variostriatum Orig Desc Text

Cite This Page

Bishop, I. (2016). Gomphonema variostriatum. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/gomphonema_variostriatum

Responses

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