Diatoms of North AmericaDiatoms of North America

Platessa stewartii

(R.M.Patrick) Potapova 2012

Platessa Stewarti Guide
  • Category
    Monoraphid
  • Length Range
    11–16 µm
  • Width Range
    5.7–7.0 µm
  • Striae in 10 µm
    14–18
  • Synonyms
    Planothidium stewartii (R.M.Patrick) Lange-Bert. in Krammer and Lange-Bert.

Identification

Platessa stewartii LM7 Platessa stewartii LM1 Platessa stewartii LM2 Platessa stewartii LM5 Platessa stewartii LM4 Platessa stewartii LM3 Platessa stewartii LM1
View image metadata Type
Platessa stewartii SEM1 Platessa stewartii SEM3 Platessa stewartii SEM2 Platessa stewartii SEM4

Description

Valves are elliptic. Both valves have a linear axial area. The central area on the raphe valve is transapically rectangular, often reaching the valve margin. The central area on the rapheless valve is small and often asymmetric. The striae are radiate and biseriate. The raphe is straight, filiform and lacks terminal fissures. Distal external raphe ends are slightly expanded and straight. Proximal external raphe ends are expanded and sharply turned to one side. Areolae are round. There is a row of areolae on the valve mantle, with one areola at the end of each stria.

Autecology

Platessa stewartii was shown to have preference for a low calcium content and low conductivity optimum of 134 μS/cm (Potapova and Charles 2003).

Original Description

Valvae ellipticae, 16 μ longae, 7.5 μ latae, area axiali angusta, costis tenuibus 14 in 10 μ, serie duplici punctorum parvorum interpositu

  • Basionym
    Achnanthes stewartii
  • Author
    R.M.Patrick 1945
  • Length Range
    16 µm
  • Width
    7.5 µm
  • Striae in 10µm
    14

Original Images

Orig Ill Plstew
Orig Descr Plstew

Cite This Page

Potapova, M. (2010). Platessa stewartii. In Diatoms of North America. Retrieved April 27, 2024, from https://diatoms.org/species/platessa_stewartii

Responses

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