Fistula

The fistula is an isolated tube, or pore near the valve central area. The fistula has a single slit-like external opening. The structure opens to the valve interior by either a single circular opening, or a transapical linear array of up to five circular to elliptic openings. Internally, the fistula is domed and hymenate.

A fistula is present in the genera Proschkinia and Fistulifera. The structure is analogous to the stigma (but not homologous).

Citations

Majewska, R., Bosak S., Frankovich, T.A., Ashworth, M.P., Sullivan, M.J., Robinson, N.J., Lazo-Wasem, E.A., Pinou, T., Nel. R., Manning, S.R., and Van de Vijver, B. (2019) Six new epibiotic Proschkinia (Bacillariophyta) species and new insights into the genus phylogeny. European Journal of Phycology 1-23

Publication Link: 10.1080/09670262.2019.1628307
Lange-Bertalot, H. (1997) Frankophila, Mayamaea und Fistulifera: drei neue Gattungen der Klasse Bacillariophyceae Archiv fur Protistenkunde 148: 65-76

Fistula — Internal view, mid-valve of Proschkinia browderiana showing fistula.