Fibula

Internal strut that provides structural support to the canal that contains the raphe. Plural form is fibulae. The fibulae extend transapically from the raphe canal to the valve face. Examples of genera having fibulae include Denticula, Nitzschia, and Surirella. From Latin for clasp, pin, or brooch.

Alternative Terms

keel puncta
Nitzschia Kurzeana  Sem
Image Credit: Sarah Hamsher
An internal view of a valve of Nitzschia kurzeana, showing the fibulae.
N Kurzeana Fibulae2
Image Credit: Sarah Hamsher
An LM image of Nitzschia kurzeana, showing the fibulae.
S Ovalis Fibulae
Image Credit: Jonathan English
Surirella ovalis possesses fibulae that support the marginal raphe canal. Note that fibulae should not be confused with costae.