Late Cretaceous follicular fruits from southern Sweden with systematic affinities to early diverging eudicots

Abstract

Eight new species in seven new genera of follicular fruits are described from the Late Cretaceous of southern Sweden. They are Agapitocarpus emisxus, Chontrocarpus pachytoichus, Maiandrocarpus moirasmenus, Malliocarpus batrachoides, Mitocarpus elegans, Xylocarpus rhitidoides, Zeugarocarpus adroagathus and Z. leptoagathus. The fossil follicles are borne along infructescence axes or more commonly occur as isolated, dispersed fruits. Three genera, Maiandrocarpus, Mitocarpus and Zeugarocarpus, have follicles in distinct pairs borne spirally on an infructescence axis. Each follicle of a pair faces the axis with its ventral slit, which strongly indicates that the paired follicles were derived from two separate, monocarpellate flowers rather than from a single, bicarpellate flower. One genus (Malliocarpus) has follicles borne individually in the infructescence and three others (Agapitocarpus, Chontrocarpus and Xylocarpus) are known only as dispersed follicles. The paired follicles share many features with most of the dispersed follicles, including a sessile stigmatic area, a three-layered simple follicle wall, a simple vascular system composed of one dorsal and two lateral bundles, as well as a marginal-linear placentation bearing several anatropous ovules. Accordingly they are thought to belong to the same complex of taxa. The general structure of the fossils and comparison with modern angiosperms suggest that the fossils might represent an extinct lineage within or close to basal eudicots and many characters are shared with members of extant Proteaceae. © 2005 The Linnean Society of London.