Platessa stewartii
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Category
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Length Range11–16 µm
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Width Range5.7–7.0 µm
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Striae in 10 µm14–18
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SynonymsPlanothidium stewartii (R.M.Patrick) Lange-Bert. in Krammer and Lange-Bert.
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ContributorMarina Potapova - Dec 2010
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ReviewerSarah Spaulding - Feb 2012
Identification
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Type
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).
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Size Range, µm3
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Motility
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Attachment
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Habitat
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Colony
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Occurrence
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Waterbody
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Distribution
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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
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BasionymAchnanthes stewartii
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AuthorR.M.Patrick 1945
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Length Range16 µm
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Width7.5 µm
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Striae in 10µm14
Original Images
Citations & Links
Citations
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Publication Link: doi: 10.1080/0269249X.2011.644636
Links
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North American Diatom Ecological DatabaseNADED ID: 155035
Cite This Page
Potapova, M. (2010). Platessa stewartii. In Diatoms of North America. Retrieved December 26, 2024, from https://diatoms.org/species/45113/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.
Platessa stewartii
- Valves elliptic
- Axial area narrow
- Central area on raphe valve transversely rectangular
- Central area on rapheless valve small, often asymmetric
- Stria density 14-18 in 10 µm
Valves are elliptic. Both valves have a linear axial area. The central area on the raphe valve is transapically rectangular, often reaching valve margins. The central area on the rapheless valve is small and often asymmetric. Striae are radiate and biseriate. The stria density on both valves is 14-18 in 10 µm.