Ptenoplacidae Alcock, 1899 Retroplumidae is a family of heterotrematan crabs, placed in their own (monotypic) superfamily, Retroplumoidea.

Eight genera are recognised, of which all but two are only known from fossils:[2] Ten species in two genera survive in the deep sea of the Indo-Pacific region:[3] Fossil specimens ascribed to the Retroplumidae are known from the Late Cretaceous onwards, with Archaeopus antennatus in Coniacian–Maastrichtian rocks in California and Archaeopus ezoensis from Turonian–Maastrichtian rocks from Japan.

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