Glossary terms starting with "m"


The downturned side of the valve surrounding the valve face. When a frustule is viewed in girdle view, the mantle is visible.


Marginal lamina

A siliceous membrane extending from the margin in many cyclostephanoid genera with raised internal costae


Pennate diatoms having a raphe on only one valve. A monoraphid diatom is a type of heterovalvar diatom. Example genera include Cocconeis, Achnanthidium, and Eucocconeis.

During the ontogeny of monorahid diatoms, a raphe begins to form on each valve. One valve completes its raphe, and becomes the raphe valve. The other valve fills its incipient raphe with silica, leaving a thickened axial rib, and becomes the rapheless valve.

The genus Nupela includes some monoraphid species and some biraphid species. In this web flora, Nupela is included in the biraphid group.


A genus with a single, validly published binomial. An example of a monotypic genus is Diprora Main, which contains only the species D. haenaensis Main.



A polysaccharide built of amino sugars and often associated with proteins. Secreted from a variety of openings in the diatom frustule. Mucopolysaccharides can be components of mucilage, a complex colloidal material used by diatoms for movement, protection, and adhesion.