The exceptionally well-preserved and diverse insect fossil record of the Baltic amber group is a unique source for science. However, bubbles and thick layers of white gaseous froth cover numerous inclusions in this type of amber, rendering their examination with traditional light microscopy impossible. Here, we show that X-ray micro-computed tomography can be an efficient tool in such cases. We scanned a completely covered rove beetle (Staphylinidae) fossil in a piece of the relatively recently discovered Rovno amber. The resulting reconstruction was detailed enough to identify the fossil as the first extinct species of Orsunius Assing, an extant genus from the systematically very challenging subtribe Medonina (Lathrobiini, Paederinae). We summarize all previous studies on the origin of gaseous inclusions around fossil specimens in Baltic amber and discuss the technical challenges of using µ-CT where a mostly hollow specimen is surrounded by bubbles of the same density. Since recent Orsunius exclusively occur in the Oriental biogeographic region, we discuss the possible climate change driven speciation scenarios between Orsunius electronefelus sp. nov. and the former. urn:lsid:zoobank.org:pub:8ECD641E-629F-46DC-BC81-217C529ACA84.