The Staphylinidae, or rove beetles, is the most species-rich family known on the planet, comprising 32 subfamilies and more than 58 000 described species. The Mesozoic staphylinids are of great significance for understanding the origin and early evolution of the whole family. The Mesozoic terrestrial strata are well developed in the territory of Transbaikalia, Russia. Since Dr. Ryvkin reported some staphylinids from the region in 1990, no additional impression fossils have been reported from this region.

Recently, a PhD student CAI Chenyang and Dr. E. V. YAN from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences together with Dr. D. V. VASILENKO from Borissiak Paleontological Institute, Russian Academy of Sciences, reported a new rove beetle species, Sinoxytelus transbaicalicus, from the Urey locality (Urey beds, Early Cretaceous?), Transbaikalia, Russia. The genus Sinoxytelus was originally described in 2010 by Dr. YUE Yanli from Capital Normal University, and it was placed in the modern oxyteline tribe Oxytelini. Sinoxytelus is a dominant genus in the Early Cretaceous Yixian Formation (approximately 125 million years ago [mya]) of northeastern China, comprising over 50% of all specimens collected from this formation. Sinoxytelus is only confined to the Early Cretaceous Jehol biota and absent in the Middle Jurassic Daohugou biota (approximately 165 mya) and the Late Jurassic Karatau beds (approximately 155 mya). Both SEMs and light microscope are applied for the new specimen recovered from the Urey locality, finding that it represents a new species of Sinoxytelus and it is well separated from other representatives by possessing a relatively large head, transverse pronotum, and slightly tapered abdomen. This is not only the first find of the extinct genus Sinoxytelus outside of China, extending its paleogeographic distribution, but also suggests that the Urey beds are probably Cretaceous in age.

In addition, according to comprehensive comparisons between the new species and other congeners, the systematic position of Sinoxytelus in the extant subfamily Oxytelinae is transferred from the tribe Oxytelini to the more basal tribe Coprophilini. This new find sheds new lights on the origin and early evolution of the staphylinid subfamily Oxytelinae.

Related information of this paper: Cai, C. -Y., Yan, E. V., Vasilenko, D. V. (2013) First record of Sinoxytelus (Coleoptera: Staphylinidae) from the Urey locality of Transbaikalia, Russia, with discussion on its systematic position, Cretaceous Research 41: 237–241.