• Category
  • Length Range
    32-70 µm
  • Width Range
    7.5-9.7 µm
  • Striae in 10 µm



Valves are dorsiventral and are 32-70 μm long and 7.5-9.7 μm wide. Valves taper toward rounded to rostrate ends. Striae are 12-14 in 10 μm and costae are 4-5 in 10 μm. There are 3-7 striae between costae. The dorsal margin is strongly convex and the ventral margin is moderately 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 is approximately 3-6 μm above the ventral margin reaching less than half the distance to the dorsal margin.


This taxon is often in aggregates in areas of low N/P ratio. Often epiphytic. Like other species of Epithemia, E. adnata contains endosymbiotic N-fixing cyanobacteria.

Original Description

Frustulis adnatis fuscis crassiusculis cymbiformibus opacis, saepe hyalino-marginatis, media interdum fascia transversali hyalina notatis, utrinque truncatis, plerumque binatim conjunctis.

  • Basionym
    Frustulia adnata
  • Author
    Kütz. 1833

Original Images

Frustulia adnata orig illus
Frustadnata  Orig Descr

Cite This Page

Lowe, R. (2010). Epithemia adnata. In Diatoms of North America. Retrieved June 21, 2024, from https://diatoms.org/species/epithemia_adnata


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