Prunum is a genus of sea snails, marine gastropod molluscs in the subfamily Pruninae of the family Marginellidae, the margin snails.

The separation between the genera Prunum and Volvarina is not very precise. They form together a monophyletic clade. The differences between these two genera are based on differences in the morphology of the shell, the radula, the radular cartilage, the mantle and the internal anatomy. A rather arbitrary criterion is currently used to distinguish between the two genera. The large species with a strong callus are placed in Prunum, the slender species with a thin callus in Volvarina, leaving in between many ambiguous species. To date (2010) there is no phylogenetic analysis behind the current generic placements

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