Diatoms of North AmericaDiatoms of North America

Encyonopsis descriptiformis

Bahls 3013

Encyonopsis Descriptiformis Guide
  • Category
    Asymmetric Biraphid
  • Length Range
    22.6-34.1 µm
  • Width Range
    5.6-6.7 µm
  • Striae in 10 µm
    18-20 at valve center, 20-22 near the apices

Identification

Encyonopsis Descripta 2 Encyonopsis Descripta 3 Encyonopsis Descripta 5 Encyonopsis Descripta 4 Encyonopsis Descripta 7
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Description

Valves are lanceolate with rostrate to short apiculate apices. Valves are not or only slightly dorsiventral. The axial area is narrow and close to the valve midline. The central area is large, round, and more or less symmetric. The raphe is weakly lateral, becoming filiform near the proximal and distal ends. Proximal raphe ends are weakly expanded and deflected dorsally. Distal raphe fissures are hooked toward the ventral side. Striae are radiate throughout.

Autecology

Encyonopsis descriptiformis has been collected from a few remote lakes in northwestern Montana. Here pH ranges from 6.9 to 7.4 and specific conductance from 20 to 130 µS/cm.

Upper Whitefish Lake
Credit: www.gather.com
Upper Whitefish Lake, Flathead County, Montana: type locality of Encyonopsis descriptiformis.

Original Description

Valves not or slightly dorsiventral, lanceolate with rostrate to short apiculate apices. Valve length 22.6–34.1 µm; valve width 5.6–6.7 µm. Axial area narrow, close to valve midline. Central area round, slightly asymmetric. Raphe weakly lateral, filiform near the proximal and distal ends. Proximal raphe ends weakly expanded, deflected dorsally. Distal raphe fissures hooked toward the ventral side. Striae radiate throughout, 18–20 in 10 µm near the valve center, 20–22 in 10 µm near the apices.

  • Author
    Bahls 2013
  • Length Range
    22.6-34.1 µm
  • Width
    5.6-6.7 µm
  • Striae in 10µm
    18-20 near valve center, 20-22 near the apices

Original Images

Encyonopsis descriptiformis orig illus
Encyo Descriptiformis Origdesc001

Cite This Page

Bahls, L. (2013). Encyonopsis descriptiformis. In Diatoms of North America. Retrieved November 21, 2024, from https://diatoms.org/species/encyonopsis_descriptiformis

Responses

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