• Category
  • Length Range
    20-31 µm
  • Width Range
    5.5-7.1 µm
  • Striae in 10 µm
    10-12 at the valve center, 14-16 near the apices

Identification

Description

Valves are distinctly dorsiventral, with subrostrate or rounded apices. The dorsal margin is strongly arched. The ventral margin is nearly flat or weakly concave and slightly gibbous in the middle. The axial area is narrow. The central area is small and asymmetric, rounded on the dorsal side and flat on the ventral side. The raphe is lateral, becoming reverse-lateral near the proximal ends. The proximal raphe ends are deflected ventrally, with slightly expanded terminal fissures. Distal raphe fissures are deflected dorsally. Striae are slightly radiate near the middle, becoming more strongly radiate near the apices. Two indistinct stigmata are present at the ends of two central, ventral striae. Central, dorsal areolae are easily resolved under LM and number 28-30 in 10 µm.

Autecology

Cymbella cosleyi has been collected from four lakes and rivers in Glacier National Park, Montana and Waterton Lakes National Park, Alberta. These waters have somewhat alkaline pH (7.80-8.54) and low specific conductance (92-209 µS/cm).

Bowman  Lake 3
Credit: Loren Bahls
Bowman Lake, Glacier National Park, Montana: type locality for Cymbella cosleyi.
P1000944
Credit: Barb Johnston, Parks Canada
Belly River in Waterton Lakes National Park, Alberta: historic home ground of Joe Cosley and current home of Cymbella cosleyi.

Original Description

Valves distinctly dorsiventral with subrostrate or simply rounded apices. Dorsal margin strongly arched, ventral margin nearly flat or weakly concave and slightly gibbous in the middle. Valve length 20–31 μm; valve width 5.5–7.1 μm. Axial area narrow, central area small and asymmetric, rounded on the dorsal side and flat on the ventral side. Raphe lateral, becoming reverse-lateral near the proximal pores, which are slightly expanded. Proximal raphe ends deflected ventrally, then recurved slightly toward the dorsal margin. Distal raphe ends deflected dorsally. Striae slightly radiate near valve middle, becoming more strongly radiate near apices, 10–12 at valve center, 14–16 near apices. Two indistinct stigmata at ends of middle ventral striae. Areolae easily resolved under LM, 28–30 in 10 μm.

  • Author
    Bahls 2013
  • Length Range
    20-31 µm
  • Width
    5.5-7.1 µm
  • Striae in 10µm
    10-12 at valve center, 14-16 near the apices

Original Images

Cymbella cosleyi orig illus
Cymbella cosleyi orig descr

Cite This Page

Bahls, L. (2012). Cymbella cosleyi. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/cymbella_cosleyi

Responses

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