Pleuroceratos jiewenae sp. nov.: A new Cretaceous phloeostichid beetle (Coleoptera: Cucujoidea: Phloeostichidae)

Elucidating the phylogenetic affinities of enigmatic fossils is crucial for resolving the early diversification of the superfamily Cucujoidea, a diverse group of polyphagan beetles whose relationships remain contentious. The systematic position of the Cretaceous genus Pleuroceratos known from Burmese amber has been uncertain; the genus was previously placed into Silvanidae, Sphindidae, and Cucujoidea incertae sedis. Here we describe a new species, Pleuroceratos jiewenae sp. nov., from mid-Cretaceous Burmese amber and conduct a formal phylogenetic analysis to elucidate the position of the genus. We recover Pleuroceratos as nested within the family Phloeostichidae, represented in the modern fauna by four genera of fungivorous subcortical beetles with a highly disjunct distribution range. Pleuroceratos beetles are the sole fossil members of Phloeostichidae known to date and indicate that the family begun to diversify by the mid-Cretaceous.