Tonicia is a genus of chitons in the subfamily Toniciinae of the family Chitonidae.

The genus was recently restricted to include only 12 New World species, with the more species-rich and exclusively Old World subgenus Lucilina Dall, 1882, being elevated to a separate genus. Of these 12, ten species are found in the eastern Pacific, one in the Magellan province (southern Chile, Argentina and Falkland Islands) and one in the Caribbean Sea (Florida to Barbados).

However, a study published in 2019 which used molecular systematics to compare the eastern Pacific Tonicia species suggested that there are only 9 extant species in the eastern Pacific.

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