Phrontis alba, common name the variable dog whelk, is a species of sea snail, a marine gastropod mollusk in the family Nassariidae, the Nassa mud snails or dog whelks.

[1] The variety Nassarius albus var.

nanus Nowell-Usticke, 1959 is a synonym of Phrontis karinae Nowell-Usticke, 1971 The length of the shell varies between 6 mm and 13 mm.

This species occurs in the Gulf of Mexico, the Caribbean Sea, the Lesser Antilles; in the Atlantic Ocean from North Carolina, USA to Brazil.

This Nassariidae-related article is a stub.