Fossil Uropodella (Acari: Mesostigmata: Sejidae) from Eocene Baltic amber

Image dataset for a paper of Evert E. Lindquist and Dmitry D. Vorontsov Uropodella (Acari: Mesostigmata: Sejidae), mites unchanged from Eocene past to Holocene present The first record is presented of the sejoid genus <em>Uropodella</em> (family Uropodellidae, suborder Sejida) from Baltic amber, based on a well-preserved adult male. Morphologically, the specimen is as fully advanced or modern in structure as adults of the six known extant species of <em>Uropodella</em>. The diagnosis of the fossil in distinction to the extant species justifies naming it as a new species. This record traces the genus back to the Eocene, representing the oldest validated age for a mesostigmatan genus. A key to species of the genus <em>Uropodella</em> is given. <em>Provenance and deposition.</em> The piece of Eocene Baltic amber mined at Usedom (a Baltic Sea island in Pomerania) containing the fossil mite treated herein originates from the private Collection of Christel and Hans-Werner Hoffeins (CCHH), original collection number CCHH-354-1. The piece is transferred to the collection of the Geological-Palaeontological Museum, Leibniz Institute for the Analysis of Biodiversity Change (LIB), Hamburg, Germany, collection number GPIH 05125. Syninclusion: Acari: Acariformes, only an anterior part (gnathosoma and propodosoma) not further identifiable, in the depth of amber. For imaging, a Nikon E-800 compound microscope with dry (10x) and water (40x and 60x) objectives was used. As the body of the mite was mostly non-translucent, most of the micrographs were made in reflected light that limited the resolution. Stacks of images, comprising multiple focal planes, were obtained with an Olympus OM-D E-M10-II digital camera. Final images were focus-stacked using Helicon Focus Pro 7.6.