Perforation, or pore, in the diatom valve. Usually many are grouped to form a stria. The plural form is areolae.

The shape of the areola can be important in diatom taxonomy, and may be lineolate, punctate, loculate, or in the shape of a letter C.

Alternative Terms

Singular of puncta. A general term for a round or oval perforation in the silica wall of a diatom.
A Crassipunctata Areola
Image Credit: Marina Potapova
SEM image of volae extending from the sides of an areola of Aulacoseira crassipunctata. Scale bar = 0.5 µm.
A Crassipunctata Areolae
Image Credit: Marina Potapova
A light micrograph of the valve mantle of Aulacoseira crassipunctata, showing many round areolae.
N Tripunctata Lineolate Areolae
Image Credit: Marina Potapova
An SEM image of the lineolate areolae of Navicula tripunctata. The arrow depicts one areola. These areolae are elongated in the apical direction, which is a characteristic of the genus Navicula. The areolae are arranged in rows to form the striae of the valve.