Diatoms of North AmericaDiatoms of North America

Eunotia tecta

Krasske 1939

Eunotia tecta guide
  • Category
    Eunotioid
  • Length Range
    17.8 - 28.5 µm
  • Width Range
    7.3 - 8.8 µm
  • Striae in 10 µm
    12-16

Identification

Lindsey 17 Lindsey 13 Lindsey 18 Lindsey 11 Lindsey 10 Lindsey 12
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Description

Valves are moderately arched. Valves have a convex dorsal margin, with three distinct undulations, regardless of valve length. The ventral margin is concave. The apices are blunt and nearly square . Striae are parallel in the center and become radiate toward the apices. The distal raphe slit is visible; it curves toward the dorsal margin close to the valve apices.

The original lectotype material shows variation in the size and curvature of the apices (Lange-Bertalot et al. 1996). The apices range from broadly rounded to slightly capitate.

The populations from DeKalb, Texas are similar to the lectotype material.

Autecology

The specimens shown here were collected from the epipelon of a small pond and a wetland in DeKalb, Texas. Other taxa in the assemblage included Pinnularia and Neidium taxa, desmids from the genera Cosmarium, Spirotaenium, Staurastrum, Micrasterias, and Closterium.

Other records include southern Chile (Krasske et al. 1939) and South Georgia Island (Van de Vijver et al. 2014).

Lane Allen Back Pond
Credit: Lane Allen
Photo of Back Pond in DeKelb, Texas where samples where taken.

Original Description

Eunotia tecta nov. spec. - Tafel X, Fig. 42, 43. Schalen mit konkaven Bauchrand und hochkonvexem dreiwelligem Rücken, an den Enden verdünnt, stumpf und breit gerundet. Transapikal-streifen grob, 12 - 13 in 10 μm, in der Mitte des Rückens sogar nur 10. Länge 27-34 μm, Breite 8 - 9 μm. - Verwandt mit E. triodon, doch kleiner und weitstreifiger.

Verbreitung ähnlich der vorigen Art: im nördlichen Gebiete nur in 2 Proben vereinzelte Stücke, im Gebiete von Puyuhuapi in 12 Proben. In Moosen aus dem Lago Riso Patron (2 Proben) und aus dem Spritzwasser seiner Wasserfälle. Im Muggelbach, Wildbach, Rio Tronador und Gletscherfluß als Steinbewuchs zwischen Algen , sowie in den 3 Proben aus dem Teiche auf der Dachstein-Westplatte. - Die Art scheint also ebenfalls kühlere und gut durchlüftete Gewässer zu lieben.

  • Author
    Krasske 1939
  • Length Range
    27 - 34 µm
  • Width
    8 - 9 µm
  • Striae in 10µm
    12 - 13

Original Images

Eunotia tecta orig photos
Eunotia tecta orig desc

Cite This Page

Sahlmann, L. (2022). Eunotia tecta. In Diatoms of North America. Retrieved November 21, 2024, from https://diatoms.org/species/eunotia-tecta

Responses

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