Bertilanthus scanicus, a New Asterid Flower from the Late Cretaceous (Late Santonian–Early Campanian) of Scania, Sweden

Abstract

A new genus and species of fossil flowers, Bertilanthus scanicus, is described from the Late Cretaceous of southern Sweden. The flowers of B. scanicus are actinomorphic and bisexual with an inferior ovary. Perianth and androecium are pentamerous. The sepals are small and free, and calyx aestivation is apert; petals are larger, and aestivation of corolla is imbricate. The androecium consists of a single whorl of stamens opposite the petals. The anthers are dithecate, tetrasporangiate, sagittate, and dorsifixed. Pollen observed in the flower is minute and oblate to spheroidal with three colpi and a tectate-punctate pollen wall. The gynoecium is formed from two carpels, and there are two free and stout styles. The epidermal cells of the styles are palisade shaped and form a distinct radiating pattern. The ovary is unilocular with numerous anatropous ovules borne on two intruding parietal placentae. There is a distinct five-parted nectary disk inserted between perianth and styles. The fruit was probably dry and capsular with apical dehiscence between the styles. Bertilanthus scanicus shares the presence of the unusual radiating palisade cells of the styles with Silvianthemum suecicum, another taxon described from the Åsen locality based on fossil flowers. Other critical features shared between Bertilanthus and Silvianthemum, including minute, tectate-punctate pollen, papillate-spiny extension of the palisade cells, free and stout styles, unilocular ovary, parietal placentation with placentae extending almost to the center of the ovary, and numerous anatropous ovules with reticulate surface, indicate that the two genera are closely related and also link these fossils to extant Quintinia, currently placed in the Paracryphiaceae (Paracryphiales) in the asterid clade.