Partectum

A bulbous chamber on the inside of the valvocopula. Found only in the genus Mastogloia. Usually arranged in a row on each side of the valvocopula, together forming the partectal ring. Plural form is partecta.

The partecta secrete mucilage to the outside of the diatom cell through relatively large pores, the partectal pores, in the wall of the valvocopula. These pores are connected to the partecta by the partectal ducts.

Alternative Terms

chamber
A synonym for partectum.
locule
An alternate term for partectum, used in some of the older literature (Stoermer et al., 1964).
Partectum2
Image Credit: Pat Kociolek
Light micrographs of Mastogloia smithii. On the left, a high level of focus showing the valve face. On the right, a deeper level of focus revealing the valvocopula, with a row of partecta on each side.
Partectum
Image Credit: Loren Bahls
Light micrographs of the valvocopula of M. pumila. On the left, the entire valvocopula. On the right, several partecta, with one partectum marked by an arrow.