• Category
  • Length Range
    19-36.8 µm
  • Width Range
    4.4-5.8 µm
  • Striae in 10 µm
  • Synonyms
    Stauroneis smithii fo. incisa (Pant.) Hust. 1957



Valves are narrowly lanceolate, with subtle marginal undulation and apiculate apices. The axial area is narrow and linear. The raphe is filiform. Striae are fine and parallel throughout the valve. In many specimens, or in less than optimal illumination, striae may not be visible. Pseudoseptae are present at both apices and are visible at high and lower focal planes in LM. The stauros is robust and rectangular.


In a 2013 US Geological Survey examination of wadeable streams in the southeastern US, Stauroneis smithii var. incisa was found to be rare (<1% of a 600 valve count) in more than 20 streams spanning Virginia, North Carolina, South Carolina, and Geogia. Camburn (1977), in his robust examination of diatom flora seasonality in Long Branch Creek, South Carolina, found this taxon to be mostly rare in counts, but occasionally common and even sometimes abundant. Camburn observed that S. smithii var. incisa was most abundant in late summer/early fall and that the species exhibited a preference for epilithic substrates, regardless of current.

Original Description

  1. Stauroneis Smithii Grün, var incisa Pant. n. v.

Valvis maxime convexis, 18'9 µ longis, 5'4 µ latis, late lanceolatis, acutis, medio valvae constrictis; rhaphe directa, stauro transverso dilatato; striis transversis, parallelis, 33 in 10 µ, usque ad apicem non percurrentibus, propter convexitatem valvae quasi pulvinulos quatuor constituentes. Seeschlamm : Siófok (tb. II, fig. 45).

  • Author
    Pant. 1902
  • Length Range
    18.9 µm
  • Width
    5.4 µm
  • Striae in 10µm

Original Images

Stauroneis Smithii Var Incisa Orig Desc Plate
Stauroneis Smithii Var Incisa Orig Desc Text

Cite This Page

Bishop, I. (2016). Stauroneis smithii var. incisa. In Diatoms of North America. Retrieved July 19, 2024, from https://diatoms.org/species/stauroneis_smithii_var._incisa


The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Stauroneis smithii var. incisa 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.