Epithemia sorex

Kützing 1844      Category: Epithemioid
BASIONYM: Epithemia sorex Kützing 1844

Epithemia reicheltii

 

Epithemia turgida
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LM scalebar = 10 µm = 40 pixels.

Observations

Contributor: Rex Lowe - December 2010
Length Range: 20-33 µm
Width Range: 7.3-9 µm
Striae in 10 µm: 12-15

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.

Original Description

Basionym: Epithemia sorex
Author: Kützing 1844
Length Range: 25 µm
Striae in 10 µm: 5.3 costae in 10 μm

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.

Original Images

Cite This Page:
Lowe, R. (2010). Epithemia sorex. In Diatoms of the United States. Retrieved May 22, 2013, from http://westerndiatoms.colorado.edu/taxa/species/epithemia_sorex

Species: Epithemia sorex

Contributor: Rex Lowe

Reviewer: Sarah Spaulding

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Image Credit: Rex Lowe

  1. Valves strongly dorsiventrally arched
  2. Raphe canal arches almost to the dorsal margin
  3. Striae 12-15 in 10 μm
  4. Cells relatively small

Valves are strongly dorsiventrally arched 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.

Compare

Epithemia sorex is more strongly convex on the dorsal margin than either E. adnata or E. turgida. In Epithemia sorex, the raphe canal arches to nearly the dorsal margin, while in E. adnata and E. turgida the raphe canal arch reaches less than half the distance from the ventral to the dorsal margin.

Epithemia adnata

Epithemia turgida

Citations

Krammer, K. and Lange-Bertalot, H. (1988). Bacillariophyceae. 2. Teil: Bacillariaceae, Epithemiaceae, Surirellaceae. In: Ettl, H., J. Gerloff, H. Heynig and D. Mollenhauer (eds.) Susswasserflora von Mitteleuropa, Band 2/2. Gustav Fisher Verlag, Jena.

Kützing, F.T. (1844). Die kieselschaligen Bacillarien oder Diatomeen. Nordhausen. 152 pp., 30 pls.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Epithemia sorex CAS

North American Diatom Ecological Database (NADED)

NADED ID: 32006

Autecology Discussion

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.

Images

SEM of E. sorex epiphytic on Cladophora in the Eel River, a N-limited river in California.

Credit/Source: Rex Lowe

Habits

Size Range

1001-10,000 µm3 (ie Diatoma vulgaris)

Motility

moderately motile (e.g. Navicula tripunctata)

Attachment

prostrate (e.g. mucilage pad)

Habitat

benthic

Colony

solitary

EMAP Assessment

Sampling for the Environmental Protection Agency (EPA) western Environmental Monitoring and Assessment Program (EMAP) study was completed during the years 2000-2004 (see citations at bottom of this page). Streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming). Over 1200 sites on streams and rivers in 12 western states (Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington and Wyoming) were selected for sampling based on a stratified randomized design. This type of design insures that ecological resources are sampled in proportion to their actual geographical presence. Stratified randomized design also allows for estimates of stream length with a known confidence in several “condition classes” (good or least-disturbed, intermediately-disturbed, and poor or most-disturbed) for biotic condition, chemistry and habitat.

EMAP Distribution

Epithemia sorex

Distribution

The distribution map represents the relative abundance of this Epithemia sorex in the western EMAP study. Relative abundance is a measure of the proportion of cells of this species based on a "fixed count" of 300 total diatom cells counted and identified. Each of the western EMAP sample sites is shown, either with a black dot for sites where Epithemia sorex was not recorded, or with a red circle indicating the relative abundance of Epithemia sorex.

Note that the size of the proportional symbols varies between species to help show both abundant and rare species.

Scale for the map to the left

EMAP Response Plots

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.

EMAP citations

Results are published in:

Johnson, T., Hermann, K., Spaulding, S., Beyea, B., Theel, C., Sada, R., Bollman, W., Bowman, J., Larsen, A., Vining, K., Ostermiller, J., Petersen, D. Hargett, E. and Zumberge, J. (2009). An ecological assessment of USEPA Region 8 streams and rivers. U.S. Environmental Protection Agency Region 8 Report, 178 p.

Stoddard, J. L., Peck, D. V., Olsen, A. R., Larsen, D. P., Van Sickle, J., Hawkins, C. P., Hughes, R. M., Whittier, T. R., Lomnicky, G. A., Herlihy, A. T., Kaufman, P. R., Peterson, S. A., Ringold, P. L., Paulsen, S. G., and Blair, R. (2005). Environmental Monitoring and Assessment Program (EMAP) western streams and rivers statistical summary. U.S. Environmental Protection Agency Report 620/R-05/006, 1,762 p.

Stoddard, J. L., Peck, D. V., Paulsen, S. G., Van Sickle, J., Hawkins, C. P., Herlihy, A. T., Hughes, R. M., Kaufman, P. R., Larsen, D. P., Lomnicky, G. A., Olsen, A. R., Peterson, S. A., Ringold, P. L., and Whittier, T. R. (2005). An ecological assessment of western streams and rivers. U.S. Environmental Protection Agency Report 620/R-05/005, 49 p.