Excorallana delaneyi n. sp. was found associated with the sponges Halichondria sp. and Hymeniacidon sp. in St. Joseph Bay, Florida. Excorallana delaneyi is most similar to E . berbicensis Boone, 1918 described from Brazil, but it can be distinguished from that species and other members of the genus by the shape and spination of the uropods and pleotelson. A key is presented to separate E. delaneyi and the other seven species of Excorallana that lack lateral notches in the pleotelson.

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... al differences between the subadults and adults of E. delaneyi are described, and possible taxonomic problems resulting from such differences in other members of the genus are discussed. Based on field observations and known life history pattems for some members of the genus Excorallana, we consider E . delaneyi to be an intermittent fish parasite which lives and reproduces in a sponge domicile between feedings.