A taxonomic and morphological re-evaluation of “Halitherium” cristolii Fitzinger, 1842 (Mammalia, Sirenia) from the late Oligocene of Austria, with the description of a new genus

The fossil sirenian material from the upper Oligocene Linz Sands of Upper Austria is reviewed and re-described in detail following a recent approach on the invalidity of the genus Halitherium Kaup, 1838. This morphological study provides the first evidence for the synonymy of “Halitherium” cristolii Fitzinger 1842, “H.” abeli Spillmann, 1959 and “H.” pergense (Toula, 1899), supporting the hypothesis that only a single species inhabited the late Oligocene shores of present-day Upper Austria. In the course of the taxonomic revision of the “Halitherium” species-complex, this taxon is now assigned to the new genus Lentiarenium Voss gen. nov. It represents a more derived sirenian compared to Eocene and early Oligocene taxa distributed across Central Europe and North Africa, which is in accordance with the stratigraphical data. An updated inventory list of all identifiable and referable skeletal material is provided, including a detailed synonymy list for the new taxonomic combination.