Female harpacticoid copepod specimens representing an undescribed species of Peltidium (Peltidiidae) were found from an unidentified species of Sargassum during a series of samplings carried out in 2014 in Tampa Bay, Florida, U.S.A. The new species, Peltidium camilae, is similar to P. nichollsi Geddes, 1968 and P. lerneri Geddes, 1968. These species share the female exopod of leg 5 with two inner and three apical setae, the second endopodal segment of leg 1 with three setae, and the third endopodal segment of legs 2-4 with three, five and four setae, respectively. Peltidium camilae n. sp. can be distinguished from P. nichollsi and P. lerneri by having a shorter endopod relative to the exopod on legs 2-4, apical claws on the terminal exopodal segment of leg 1 that are as long as the first exopodal segment of leg 1, and subequal middle and inner apical setae on the exopod of leg 5. This is the first record of the family Peltidiidae from the Gulf of Mexico.