Pleurosira laevis

(Ehrenberg) Compère 1982      Category: Centric
BASIONYM: Biddulphia laevis Ehrenberg 1843
SYNONYM(S): Cerataulus laevis (Ehrenberg) Ralfs in Pritchard 1861 

Pleurosigma inflatum


Prestauroneis integra

LM scalebar = 10 µm = 20 pixels.


Contributor: Pat Kociolek - March 2011
Diameter: 65–120 µm
Rows of areolae in 10 µm: 12-13 at the margin of valve


Valves circular to elliptical. The valve face is slightly hemispherical. Two ocelli are present, positioned opposite one another, composed of fine rows of porelli. The ocelli are not the same size; one is much larger than the other. Two-three rimoportulae are present, each with a small, hyaline area surrounding the opening. Striae are radiate and number 12-13 in 10 μm at margin of valve face. Areolae are in short radial rows at the valve margin, irregularly arranged in central part of valve. Areola density is 12-18 in 10 μm. Spinules are present across valve face and at the margin.

Living cells are joined in zig-zag chains, with cells attached to one another by mucilage at the opposing cell’s ocelli.

Kociolek et al. (1983) reported this species from inland habitats in Ohio, and a related species was recently described from India (Karthick and Kociolek 2011). Images from Krammer and Lange-Bertalot (1991) are more similar to those depicted here (from California) than the images from Kociolek et al. More research is needed to clarify the relationships of these populations.

Original Description

Basionym: Biddulphia laevis
Author: Ehrenberg 1843
Diameter: µm
Rows of areolae in 10 µm:

Original Description

Original Images

Cite This Page:
Kociolek, P. (2011). Pleurosira laevis. In Diatoms of the United States. Retrieved September 28, 2016, from

Species: Pleurosira laevis

Contributor: Pat Kociolek

Reviewer: Sam Rushforth


Krammer, K. and Lange-Bertalot, H. (1991). Bacillariophyceae. 3. Teil: Centrales, Fragilariaceae, Eunotiaceae. In Ettl, H., Gerloff, J., Heynig, H. & Mollenhauer, D. (Eds.). Süsswasserflora von Mitteleuropa. 2(3): 1-576. Gustav Fisher Verlag, Stuttgart, Germany.

Links & ID's

Index Nominum Algarum (INA)

Original INA

California Academy of Sciences (CAS)

Pleurosira laevis CAS

North American Diatom Ecological Database (NADED)

NADED ID: 158001

Autecology Discussion


A small mother cell (left) and auxospore of Pleurosira laevis. The auxospore is 121 µm in length. Cells are from the Caloosahatchee River, Fort Myers, Florida (Lat: 26.6582, Long: -81.8532).

Credit/Source: Emily Nodine

A group of cells of Pleurosira laevis in girdle view, along with an auxospore in valve view. The auxospore is 129 µm in length. Cells are from the Caloosahatchee River, Fort Myers, Florida (Lat: 26.6582, Long: -81.8532).

Credit/Source: Emily Nodine