Keel | Glossary - Diatoms of North America

Keel

A keel is a thickening of silica that contains the raphe within a canal. The keel elevates the raphe from the surface of the valve, allowing maximal contact of the raphe with surfaces for motility.

A number of genera possess a keel, including Nitzschia, Iconella and Entomoneis.

Citations

Ross, R., Cox, E.J., Karayeva, N.I., Mann, D.G., Paddock, T.B.B., Simonsen, R. and Sims, P.A. (1979) An amended terminology for the siliceous components of the diatom cell Nova Hedwigia, Beihefte 64: 513-533
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.
Ruck, E.C. and Theriot, E.C. (2011) Origin and evolution of the canal raphe system in diatoms Protist 162(5): 723-737

Publication Link: 10.1016/j.protis.2011.02.003
Ruck, E.C., Nakov, T., Alverson, A.J. and Theriot, E.C. (2016) Phylogeny, ecology, morphological evolution, and reclassification of the diatom orders Surirellales and Rhopalodiales Molecular Phylogenetics and Evolution 103: 155–171

Publication Link: 10.1016/j.ympev.2016.07.023

Rhopalodia 2 — A scanning electron micrograph of a frustule of Rhopalodia. The keel of each valve is indicated by an arrow. The raphe is visible as a faint line along the edge of each keel.

Gs020021 19 — SEM of the external surface of Surirella amphioxys. The raised portion of the undulation is a porca. The raised canal (keel) contains the raphe is at the top of the image.

S Ovalis Fibulae — Surirella ovalis possesses fibulae that support the marginal raphe canal. Note that fibulae should not be confused with costae.