Chamaepinnularia mediocris | Species - Diatoms of North America

Category

Symmetric Biraphid
Length Range

9-16 µm
Width Range

2.7-3.0 µm
Striae in 10 µm

20-24

Synonyms

Pinnularia mediocris (Krasske) Mills 1935

Contributor

Megan Otu, Sarah Spaulding - Mar 2011
Reviewer

Loren Bahls - Jan 2012

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Identification

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Description

Valves are linear to broadly oval, with rounded apices and a gibbous middle. The axial area is narrow near the apices, becoming wider near the central area. The central area is a transverse fascia: in some specimens it extends to the valve margins, in other specimens short irregular striae are present at the margins. The raphe is filiform and slightly arched. Terminal nodules are distinct. The striae are parallel and composed of a single, elongate areola on the valve face. A smaller areola is positioned on the valve mantle. Externally, the proximal raphe ends are straight. Internally, the proximal raphe ends are slightly deflected unilaterally.

Autecology

Chamaepinnularia mediocris is found in oligotrophic waters of the US. On the main identification page we document images of specimens from Maine, Pennsylvania and Wyoming. This species was relatively uncommon in the western EMAP survey of US streams and rivers, and never occurred in high relative abundance.The cells from high elevation lakes of Grand Teton National Park are at the small end of the size spectrum, while cells from the eastern US are larger. In the western EMAP survey, C. mediocris was found at pH between 7 and 8.

Size Range, µm3

11-100
Motility

Slightly motile
Habitat

Moist habitats Benthic
Colony

Solitary
BCG

BCG 2
Waterbody

Inland
Distribution

Western rivers 2004 California coastal rivers 2017 Northeast lake sediments Great Lakes inventory
Learn more about this

Credit: Sarah Spaulding

Holly Lake, in Grand Teton National Park, Wyoming, is one of the high elevation lakes where Chamaepinnularia mediocris is found.

Original Description

Schalen linear mit bauchiger Mitte und gerundeten Enden. Streifen krätfig, die beiden mittleren schwächer, parallel, 22-24 in 10 µ. Area schmal, in der Mitte rundlich erweitert. Raphe sehr zart. Lang 9-12 µ, breit 2,5-3 µ.

Basionym

Navicula mediocris
Author

Krasske 1932
Length Range

9-12 µm
Width

2,5-3 µm
Striae in 10µm

22-24

Original Images

Citations & Links

Citations

Cite This Page

Otu, M., Spaulding, S. (2011). Chamaepinnularia mediocris. In Diatoms of North America. Retrieved December 16, 2024, from https://diatoms.org/species/46500/chamaepinnularia_mediocris

Responses

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