The part of a valve that extends from the valve face, forming the edge of the valve. When a frustule is viewed in girdle view, the mantle is visible.
Image Credit: Marina Potapova
The mantle of Aulacoseira alpigena is ornamented, while the valve face has marginal arealae.
The mantle of Stephanodiscus yellowstonensis is rounded at the mantle/valve face interface.