Axial costa

Auxospore

 

Axial plate

A narrow ridge of silica along the axial area on the inside of the valve bordering the raphe.

Mastogloia smithii is an example which has two axial costae. Together they form the sides of a groove, or gutter (Paddock and Kemp, 1990), widening slightly at the central nodule and stopping short of the distal raphe ends.

See also costa.


Alternative Term

longitudinal rib

Similar to an axial costa, but in general more rounded and relatively wider. Found in the genus Frustulia for example.

Citations

Lee S.S., Gaiser E.E., Van de Vijver, B., Edlund, M.B., and Spaulding, S.A. (2014). Morphology and typification of Mastogloia smithii and M. lacustris, with descriptions of two new species from the Florida Everglades and the Caribbean region. Diatom Research. doi:10.1080/0269249X.2014.889038

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.

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.