Diatoms of North AmericaDiatoms of North America

Epithemia sorex

Kütz. 1844

Epithemia Sorex Guide Copy
  • Category
    Epithemioid
  • Length Range
    20-33 µm
  • Width Range
    7.3-9 µm
  • Striae in 10 µm
    12-15

Identification

Esor Mo000125 8Ed 1 Esor Ih0440 1Ed 1 Esor Mo000125 5Ed Esor Ih0440 2Ed 1 Esor Mo000125 7Ed Esor Mo000125 4Ed Esor Mo000125 6Ed
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Epithemia sorex SEM1

Description

Valves are dorsiventral and are 20-33 μm long and 7.3-9 μm wide. Valves taper toward rounded to rostrate ends. Striae are 12-15 in 10 μm and costae are 6-8 in 10 μm. There are 2 (sometimes 3) striae between costae. The dorsal margin is strongly convex and the ventral margin is weakly concave. The raphe canal lies against the ventral margin at distal ends of the valve and arches toward the dorsal margin in the valve center. The central arch of the canal reaches almost to the dorsal margin.

Autecology

Similar to other species of Epithemia, E. sorex frustules contain nitrogen-fixing endosymbiotic cyanobacteria which enable this taxon to become abundant in microhabitats with a low N/P ratio. It is frequently very abundant as an epiphyte on Cladophora and other coarse filamentous algae in western rivers and similar N-limited habitats.

Esorexepiphytes009
Credit: Rex Lowe
SEM of E. sorex epiphytic on Cladophora in the Eel River, a N-limited river in California.

Original Description

E. minuta a latere secundario dorso valde convexa, apicibus acutis prominentibus; striis convergentibus (in 1/100"' parte 12); a latere primario elliptica, apicibus abtusiusculis prominentibus.

  • Author
    Kütz. 1844
  • Length Range
    25 µm
  • Striae in 10µm
    5.3 costae in 10 μm

Original Images

Epithemia sorex orig illus
Epsor Orig Descr

Cite This Page

Lowe, R. (2010). Epithemia sorex. In Diatoms of North America. Retrieved April 25, 2024, from https://diatoms.org/species/epithemia_sorex

Responses

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