• Category
  • Length Range
    67.2-113.0 µm
  • Width Range
    13.7-18.5 µm
  • Striae in 10 µm



Valves are linear-lanceolate with capitate apices. The axial area is moderately wide. Raphe branches and adjacent longitudinal ribs are slightly curved. Proximal and distal ends of the longitudinal ribs are indistinct. The central area is linear-elliptic and 3.0-5.1 µm wide. A single row of areolae borders the outside of each longitudinal rib. These two rows of areolae continue through the central area where they enclose a smaller space of the same linear-elliptic shape. The two rows of areolae meet at each apex, where they enclose a rounded terminal area that lacks a prominent porte-crayon. Transapical striae are parallel to weakly radiate, becoming weakly convergent near the apices. Reduced striae radiate around the apices. Areolae number 24-26 in 10 μm.


Frustulia esandalliae is known only from a ponded spring (livestock reservoir) in the high desert of eastern Oregon (photos below). The water in this pond is presumably calcareous with a moderately high electrolyte content. The morphologically similar Frustulia alfinitosilviae from Sardinia occupies a similar habitat: bottom sediments of ponds that dry out during summer and have a high electrolyte content.

Dicks Spring
Credit: Sage Clegg, Adventurers and Scientists for Conservation
Dick's Spring, Lake County, Oregon.
Dicks Spring Cow Pond
Credit: Sage Clegg, Adventurers and Scientists for Conservation
Dick's Spring Cow Pond, Lake County, Oregon. The sample containing Frustulia esandalliae was a composite of materials collected from the spring and the pond.

Original Description

Valves are linear-lanceolate with broadly capitate to subcapitate apices. Valve length 67.2-113.0 μm; valve width 13.7-18.5 μm. Axial area is moderately wide and occupied by a robust raphe sternum, the branches of which are nearly straight to slightly bowed in smaller specimens. Centraltwo rows of areolae forming an apically elongate ellipse between the proximal raphe ends. Terminal nodules are spatulate and lack a “porte-crayon”. Proximal and terminal raphe fissures indistinct. Transapical striae parallel to weakly radiate, becoming weakly convergent near the apices, 25-26 in 10 μm. Areolae in the striae 24-26 in 10 μm. SEM.—With additional magnification, external SEM images (Figs. 76, 77) show that the terminal and proximal raphe ends are T-shaped.

  • Author
    L.L.Bahls 2014
  • Length Range
    67.2-113.0 µm
  • Width
    13.7-18.5 µm
  • Striae in 10µm

Original Images

Frustulia esandalliae orig illus

Cite This Page

Bahls, L. (2016). Frustulia esandalliae. In Diatoms of North America. Retrieved July 22, 2018, from https://diatoms.org/species/frustulia_esandalliae


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