• Category
  • Length Range
    14-75 µm
  • Width Range
    11-35 µm
  • Striae in 10 µm
  • Synonyms
    Surirella ovata var. ovalis (Bréb.) Kirchner
    Suriraya ovalis (Bréb.) Pfitzer



The valves are extremely variable throughout their vegetative cell cycle. Their length ranges from 16 to 61.5µm and their width from 11 to 35µm. The valves are all heteropolar and the poles vary according to valve length. The longest valves, between 41 and 75µm, had two cuneate apices, one being broader than the other. The middle length valves, between 31 and 34µm, had one cuneate apex and one broadly rounded apex. The smallest valves, between 14 and 27µm, had two broadly rounded apices, one being broader than the other. The intermediate sizes showed transitional states. Most of the valve faces were concentrically undulate with one or two undulations. The costae on the valve face are relatively coarse at 14-17 in 10 µm and every third or fourth costa in the margin is raised above the others, corresponding to the fibulae on the interior of the valve. The fibulae are marginal and are 5-6 in 10 µm.

Under SEM, the striae between the costae become visible. There are two rows of slit areolae irregularly orientated between each of the costae. Near the valve margin where the concentric undulation occurs and the raised costae begin, the striae split into as many as five rows. These striae lead into an areolated depression, or pseudoinfundibulum.

Krammer and Lange-Bertalot (1987) note on the type material that there is a single portula on the mantle between the fibulae. They also were not able to observe the areolae on the type material due to possible acidic degradation.


Original Description

S. ovalis Nob. Falaise. Se rapproche de la précédente, mais elle n'a point ses quatre ailes profondément cannelées.

  • Basionym
    Surirella ovalis
  • Author
    Bréb. 1838

Original Images

Surirella ovalis orig illus

Citations & Links


Cite This Page

English, J. (2011). Surirella ovalis. In Diatoms of North America. Retrieved July 24, 2024, from https://diatoms.org/species/surirella_ovalis


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