• Synonyms
    Surirella clypeus (Ehrenb.) Kütz.
    Cocconeis clypeus Ehrenb. 1838



Valves are large, heavily bent, and saddle-shaped. The central area is separated from the rest of the valve by a rounded rectangular hyaline area and then split down the middle by another hyaline line oriented down the longest dimension of the rectangle. Areolae are organized into irregular rows that are perpendicular and on either side of the middle hyaline line. Fibulae begin outside of the central area and radiate out from the rectangular hyaline area in concentric waves. Each fibula near the ends of the rectangle is short and irregularly ornamented with areolae that may occur in rows. Fibulae along the length of the rectangle may be twice as long but contain most of their areolae toward the outer and inner edge with a relatively unornamented area in the middle (i.e., a hyaline ring, Krammer and Lange-Bertalot 1986).


Campylodiscus clypeus was first collected by Ehrenberg in a diatomite sample from Františkovy Lázné Spa, West Bohemia, Czech Republic in 1838 (Poulíčková and Jahn 2007). This area has been protected since 1992 as a unique saline locality.

In 1839, Ehrenberg reported it again in Eger, which is close to the original location. Both localities are part of Cheb Basin which is characterized by post-glacial organogenic sediments such as peat, fen-peat, and diatomaceous earth. The makeup of the sediment is influenced by the composition of mineral water rising from the crystalline basement of the Cheb basin which may consist of sodium sulfate, sodium bicarbonate, or calcium-magnesium bicarbonate. There is no evidence that there are any living C. clypeus at the type locality today (Poulíčková and Jahn 2007).

Specimens of C. clypeus observed here have been collected in periphyton samples from Salt Lake, Minnesota and Stink Lake, South Dakota. Generally, it is considered an epipelic diatom that lives at the bottom of lakes. This taxon has been reported widely around the world including areas in Europe, Africa, North America, and Australia. It is more common in brackish-marine lagoonal seas and hypersaline lakes. However, it has also been reported from historical samples from the Thames River, England (Poulíčková and Jahn 2007).

Original Description

268. Cocconeïs? Clypeus, Rund-Schildchen.

G. testula orbiculari, ampla, plana, leviter involuta, extus laevi, intus interrupte radiata.

Cocconéide? Clypée, à carapace orbiculaire, grande, plate, légèrement courbée, extérieurement lisse, intérieurement rayée.

Aufenthalt: Fossil im Kieselghr von Franzensbad in Böhmen.

Zwischen der Navicula viridis von Franzensbad findet es sich selten als runde strahlige Scheiben von ansehnlichem Durchmesser. Man könnte in dieser grössten Art der Gattung eine Verwandschaft zu Actinocyclus finden. Sie besteht aus 2 eng aneinander liegenden, sehr dünnen, flachen, runden Platten, welche so gebogen sind, als ob sie sich an einen cylindrischen Pflanzentheil eng angeschlossen hätten. In der Mitte ist eine ungestreifte längliche Stelle und in deren Mitte wieder eine längliche klaffende Oeffnung; ich sah sie aber nur auf Einer Seite. Nach dem Rande hin sind 2 Reihen durch einen glatten, unregelmässigen, bandartigen Zwischenraum getrennte Streifen oder innere Leisten, welche unterbrochenen Strahlen gleichen. Diese sehr besondere Form mag wohl bei noch schärferer Auffassung der Charactere eine besondere Gattung verlangen. Die Streifen sind weniger regelmässig, als bei den Naviculis. Ich sah kleiner mit 5-6 Streifen auf 1/96 Linie, und grössere mit 3. -- Durchmesser der Scheibe 1/36-1/20 Linie. Eine Abbildung konnte nicht mehr aufgenommen werden.

  • Basionym
    Cocconeis clypeus
  • Author
    Ehrenberg 1838
  • Length Range
    62.92-113.25 µm

Original Images

Cocconeis Clypeus orig desc

Cite This Page

Aranda, N. (2022). Campylodiscus clypeus. In Diatoms of North America. Retrieved December 08, 2022, from https://diatoms.org/species/campylodiscus-clypeus


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