First fossil eleusinin rove beetle (Coleoptera: Staphylinidae: Osoriinae: Eleusinini) from mid-Cretaceous Kachin amber of northern Myanmar and its evolutionary implications

Eleusinini is the smallest osoriine tribe, consisting of 221 species in three genera. No fossil Eleusinini has been found until now. Here, I describe the first extinct representative of eleusinin rove beetles, Eleusis sulcata n. sp., based on a well-preserved adult specimen from the mid-Cretaceous Kachin amber in northern Myanmar. This new species is tentatively placed in the extant genus Eleusis Laporte, 1835, and it is easily distinguished from its congeners by the longitudinal sulcus on the dorsal surface of the head and complete lack of supraocular grooves. The discovery of E. sulcata n. sp. provides further evidence that Eleusinini is a relatively ancient group, originating no later than the Albian-Cenomanian boundary. Furthermore, the markedly flattened body of this new species suggests that the Eleusinini had adapted to a subcortical lifestyle under bark or in rotten wood by the mid-Cretaceous. (c) 2023 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved.