A revision of Sinotamias (Rodentia, Sciuridae, Xerinae) from eastern Europe, with a discussion of the evolutionary history of the genus

ABSTRACT

Sinotamias is a geographically and temporally widespread genus of marmotine ground squirrels from the Neogene of Asia and eastern Europe. Here, we revise the eastern European members of the genus and describe two new species from the Late Miocene of Ukraine and Moldova. The first, Sinotamias lungui sp. nov., is a small and early species that retains a complete lingual metaloph and weak metaconule of M1-2 and mesoconids on p4. The second, S. topachevskyi sp. nov., is a larger, transitional species, roughly intermediate in size and dental morphology between S. lungui and more derived S. gromovi, with a weak P4 metaconule and a three-rooted m3. We also describe additional material of S. gromovi. The three temporally successive eastern European species of Sinotamias form an anagenetically evolving lineage, evidenced by a gradual change towards more cuspate dentition with rudimentary lingual mesoloph; voluminous, posteriorly shifted metaconules; more defined posterior valley of M3; longer metalophids; and strongly arched, posteriorly tapered ectoloph of p4–m3 lacking a mesoconid. The morphological trends are accompanied by M2, M3, m2 and m3 size increase and is consistent with the biostratigraphic distribution of Sinotamias species throughout the Turolian of eastern Europe.

KEYWORDS:

• Sinotamias
• miocene
• ukraine
• moldova
• ground squirrel
• evolution

Acknowledgments

We thank the editor, Gareth J. Dyke, and two anonymous reviewers for constructive comments that greatly improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Financial support for this study was provided by a Grant to the Department of Science, Roma Tre University (MIUR-Italy, Dipartimenti di Eccellenza, Art.1 C, 314-327, L.232/2016) and by Act 211 of the Government of the Russian Federation, contract No. 02.A03.21.000.