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Raphe ledge

One or two slits, or fissures, through the valve face of monoraphid and biraphid diatoms. If two slits are present, each is called a branch of the raphe. Branches may be separated by a silica thickening called the central nodule. Raphe position may be (1) axial, along the apical axis; (2) eccentric, along one margin; or (3) circumferential, around the whole margin of the valve. From Greek for seam.

The raphe is the structure that raphid diatom cells use to move over surfaces.

Alternative Term

raphe system


Cox, E.J. (2012). Ontogeny, homology, and terminology - wall morphogenesis as an aid to character recognition and character state definition for pennate diatom systematics. Journal of Phycology 48: 1–31. 10.1111/j.1529-8817.2011.01081.x

Paddock, T.B.B. and Kemp, K.D. (1990). An illustrated survey of the morphological features of the diatom genus Mastogloia. Diatom Research 5: 73-103.

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.