The systematic position of Ehretia fossils (Ehretiaceae, Boraginales)from the European Tertiary and implications for character evolution

Ehretia fruits contain four seeds arranged in an endocarp, which is either four-parted (Ehretia I), two-parted (Ehretia II), or undivided (Ehretia monopyrena). The single parts are called endocarpids, which are one-loculed, twoloculed, or four-loculed respectively. On the basis of its two-loculed endocarp the fossil species Ehretia clausentia from the European Eocene is recognised as a representative of the Ehretia II clade as are also most other fossils of Ehretia. The fossil Ehretia hedericarpa from the European Oligocene and Miocene is the only known fossil of Ehretia with one locule per endocarpid and was therefore placed in the Ehretia I clade. Morphological and anatomical investigations of the fossils demonstrate some syn-apomorphies of the latter with the Ehretia II clade (e.g. diminution of the placenta). In a phylogenetic tree E. hedericarpa is the sister species of the Ehretia II clade. The occurrence of E. hedericarpa in Europe agrees with the assumption that it is closely allied to the Laurasian Ehretia II clade since the representatives of Ehretia I are not known from the former Laurasian Continent.