Voigt discontinuity

A Voigt discontinuity is an interruption in the stria pattern of a raphid diatom valve. This discontinuity, if present, occurs on the secondary side of a valve and marks the point of fusion of the sternum during ontogeny. It is named for M. Voigt, who first noted it in 1943.

Alternative Terms

Voigt fault
fault irregulare
Neidium Affine Var Ceylonium L 3 142
Image Credit: Teo Nakov
Light micrograph of a valve of Neidium, with two arrows indicating the Voigt discontinuities. These structures are common in Neidium, less often visible in other genera of raphid diatoms.
Image Credit: Adapted from Round et al. (1990)
This series of drawings represents the pattern of silica deposition as a raphid valve forms. At top, a narrow rib of silica, the primary side of the sternum, forms first. Next, at the poles and central nodule the primary side extends to form the secondary side of the sternum, creating the raphe slit. Finally, both sides complete the valve formation. This secondary side includes a Voigt discontinuity.
Gsn24379 02 1 Copy
Image Credit: Marina Potapova
The arrows point out the secondary side and Voigt discontinuities in this light micrograph of Navicula germainii.