New discoveries in the frog Latonia seyfriedi (Anura: Alytidae) and their impact on taxonomy of the genus Latonia

Latonia seyfriedi, the type species of the genus Latonia, was described by von Meyer (1843) based on an articulated skeleton from the middle Miocene (Serravallian) of Ohningen, Germany. Besides the holotype, four additional articulated skeletons are known from the type locality; all display only the ventral aspect. A similar frog reported by Lartet (1851) from the middle Miocene of Sansan, France was later assigned to the genus Latonia as L. gigantea based on disarticulated skull roof bones covered with sculpture. In the course of time, similar bones were recovered from numerous localities, but, because the dorsal surface of the cranial roof was not known for L. seyfriedi, they were mostly identified as L. gigantea. The crucial question of whether the skull roof bones of L. seyfriedi, especially the frontoparietal and maxilla, bear sculpture or not remained unresolved until recently, when specimen TMH 8438 from Ohningen was made available for micro-computed tomography (CT) investigations. The present study reveals that the frontoparietal is covered by pustular sculpture as in the L. gigantea neotype, and that the sculpture on the maxillae is similar in both taxa. Since other bones are also similar, we suggest that L. gigantea is a junior synonym of L. seyfriedi. Micro-CT scanning of TMH 8438 made it possible to reconstruct the original positions of the bones. It turned out that the nasals are sculptured and overlapped with the frontal processes of the maxillae as well as with the anterior end of the frontoparietal. This allowed us to reconstruct the shape and proportions of the skull.