• Synonyms
    Gomphonema constrictum var. truncatum (Ehrenb.) Gutw. 1887

Identification

Description

Valves are clavate, with tumid center. A constriction at the headpole and then broad apex creates a distinctly capitate headpole. The footpole is narrow and rounded. The axial area is straight and expanded on either side of the axial area to form a “bow-tie” shaped central area. A single, rounded external stigma opening is present in the central area. The raphe is lateral and undulate, with expanded external proximal ends. The distal raphe curves onto the mantle in the direction opposite the stigma. Striae are radiate, indistinctly punctate, and become parallel toward the headpole. Striae are strongly radiate at the footpole. A distinct apical pore field is present at the footpole. Septa and pseudosepta are present at the poles.

Autecology

Original Description

  • Author
    Ehrenb. 1832

EMAP Assessment

EMAP Distribution

Gomphonema Truncatum 40 Copy
Map 40

Response Plots

Gomphonema Truncatum Copy

Cite This Page

Kociolek, P. (2011). Gomphonema truncatum. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/gomphonema_truncatum

Responses

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