An interruption in the stria pattern of a raphid diatom valve. The Voigt discontinuity, if present, occurs on the secondary side of a valve and marks the point of fusion of the sternum during ontogeny. Named for M. Voigt, who first noted it in 1943.
Mann, D.G. (1981). A note on valve formation and homology in the diatom genus Cymbella. Annals of Botany 47: 267-269.
Round, F.E., Crawford, R.M. and Mann, D.G. (1990). The Diatoms. Biology and Morphology of the Genera. Cambridge University Press, Cambridge, 747 pp.
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)
These drawings, from top to bottom, represent the pattern of silica deposition as a valve forms. First, a narrow rib of silica, the sternum, is deposited, forming the primary side, or primary rib. Next, siliceous deposits form at the poles and central nodule and grow together to form the secondary side of the valve, sometimes forming Voigt dicontinuities.
Image Credit: Marina Potapova
The secondary side and Voigt discontinuities are evident in this light micrograph of Navicula germainii.