Hemiarthrum setulosum is a species of chiton in the family Hemiarthridae, the only member of the genus Hemiarthrum. It was previously assigned to the family Hanleyidae.

Hemiarthrum setulosum represent one of the five major clades of chitons that are living. Hemiarthrim setulosum has an incomplete lateral tract in the nerve ring. They are the only known species to have an incomplete one.

Synonym

• Hemiarthrum hamiltonorum Iredale & Hull, 1932: synonym of Hemiarthrum setulosum P. P. Carpenter [in Dall], 1876 (junior subjective synonym)

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