The first fossil Megalopsidiinae (Coleoptera: Staphylinidae) from Upper Cretaceous Burmese amber and its potential for understanding basal relationships of rove beetles

•The first fossil Megalopsidiinae is described from Upper Cretaceous Burmese amber.•Well-preserved fossil is named as Megalopinus extinctus sp. n.•Megalopinus extinctus presents evidence of possible bradytely of Megalopsidiinae.

The first definitive fossil of the peculiar monotypic rove beetle subfamily Megalopsidiinae is described as a new species Megalopinus extinctus sp. n. It represents a stem lineage valuable for the study of the early diversification of Staphylinidae, where sister group relationships of Megalopsidiinae currently remain a big controversy. This discovery corroborates the Mesozoic origin of this subfamily implied by its presumably basal phylogenetic position within Staphylinidae and hitherto available fossil record for the family. Well preserved peculiar mouthparts of M. extinctus specialized similarly with recent Megalopinus suggest the same mode of feeding in Megalopsidiinae for nearly a hundred million years.

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