• Category
  • Length Range
    32.5-58.7 µm
  • Width Range
    20.7-32.6 µm
  • Striae in 10 µm
  • Reported As
    Diploneis ovalis (Hustedt 1930, p. 249, fig. 390)



Valves are elliptic to oval with broad, round apices. The longitudinal canals are narrow, the width of one to three areolae, and follow the margin of the axial and central areas. The axial area is occupied almost completely by a broad raphe. The central area is large and orbicular, 4.9-8.5 µm wide. Striae are uniseriate and radiate throughout. Areolae are large, blocky and number 16-20 in 10 µm.

Diploneis ovalis is less common than D. krammeri, which is often misidentified as D. ovalis.


Lange-Bertalot and Reichardt (in Rumrich et al. 2000) report that D. ovalis prefers "weakly buffered, electrolyte-poor, weakly acidic waters". It is less common in the Northwest United States than D. krammeri, with which it is often confused. The specimens of D. ovalis shown on the identification page are from Lake Caroline, a small lake in the Cascade Mountains of Washington (photo below).

Lake Caroline3
Credit: Ryan Davis, Adventurers and Scientists for Conservation
Lake Caroline, Chelan County, Washington: home of Sellaphora alastos.

Original Description

  • Basionym
    Pinnularia ovalis
  • Author
    Hilse in Rabenh. 1861

Original Images

Pinnularia Ovalis Text 268X0
Pinnularia Ovalis  Descr 268X0

EMAP Assessment

EMAP Distribution

Diploneis Ovalis   Hilse Ex  Rabenhorst   Cleve 3
Map 3

Response Plots

Diploneis Ovalis   Hilse Ex  Rabenhorst   Cleve


Jul 21, 2018 - Change in name

Previously, the page for Diploneis ovalis included images for a taxon that is similar to Diploneis krammeri. The concept presented here is now in alignment with D. ovalis. - L. Bahls, S. Spaulding

Cite This Page

Bahls, L. (2014). Diploneis ovalis. In Diatoms of North America. Retrieved July 21, 2018, from https://diatoms.org/species/diploneis_ovalis1


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