Description of a new species of Ione (Isopoda: Epicaridea) parasitizing Lepidophthalmus siriboia (Decapoda: Axiidea) with the first record of the Ionidae from Brazil

A new species of parasitic isopod belonging to the genus Ione Latreille, 1818, is described from material collected in northeastern Brazil, parasitizing the branchial chamber of the intertidal burrowing shrimp Lepidophthalmus siriboia Felder & Rodrigues, 1993. The female of Ione maracatu sp. nov. is characterized by an elongated body, maxilliped with palp and spur, barbula with three lateral projections, foliaceous coxal plates, pleon with endopodites broad, and exopodites elongated, lateral plates with numerous projections, and uropod robust and uniramous. This is the eighth valid species of the genus Ione and the first record of this genus and the family from the tropical southwestern Atlantic. A distribution map of I. maracatu sp. nov., and an updated taxonomic key of all species of the genus are provided.