New Orchestina Simon, 1882 (Araneae: Oonopidae) from Cretaceous ambers of Spain and France: first spiders described using phase-contrast X-ray synchrotron microtomography

Two new species of Orchestina (Araneae: Oonopidae) are described as O. gappi sp. nov. and O. rabagensis sp. nov. from the Cretaceous of France and Spain, respectively. Two additional specimens from Spain are placed within Orchestina but not assigned to species. These formal descriptions are the oldest for the genus and the family Oonopidae. The discovery of these older Orchestina is not surprising, as the genus is considered a basal member of the Oonopidae and one of the most diverse and long-lived spider lineages. Two of the spiders were imaged at the European Synchrotron Radiation Facility using propagation phase-contrast X-ray synchrotron microtomography, demonstrating once again the enormous potential of this technique for studying fossil inclusions in amber.