We report Dermophthirius carcharhini (Monogenea: Microbothriidae) from the skin of a dusky shark, Carcharhinus obscurus (Carcharhinidae), in the southwest Indian Ocean off Umhlanga Rocks, South Africa, and Dermophthirius maccallumi from the skin of 2 bull sharks, Carcharhinus leucas, in the northern Gulf of Mexico off Cat Island, Mississippi, U.S.A. No previous report exists of a microbothriid from the western Indian Ocean or from off southern Africa or of D. maccallumi from beyond the vicinity of the Lake Nicaragua–San Juan River system. We also provide a list of hosts and localities for members of Dermophthirius.