Parasitic arthropods of sympatric opossums, cotton rats, and cotton mice from Merritt Island, Florida.

Six species of parasitic arthropods were collected from 12 opossums (Didelphis virginiana), 8 species were obtained from 28 cotton rats (Sigmodon hispidus), and 4 species were collected from 10 cotton mice (Peromyscus gossypinus) from Merritt Island, Brevard County, Florida. The flea Polygenis gwyni was the only parasite that infested all 3 host species, and it was present in very high densities (mean intensity = 73.7) on the opossums. The American dog tick, Dermacentor variabilis, and the tropical rat mite, Ornithonyssus bacoti, both infested 2 host species but were principally associated with opossums and cotton rats, respectively. All remaining arthropod species were confined to single host species, suggesting host specificity by these parasites. The atopomelid mite Didelphilichus serrifer and the myobiid mite Radfordia sigmodontis constitute new state records for Florida. The reptile tick Amblyomma dissimile is recorded from a cotton mouse for the first time; Merritt Island may represent the most northerly location for viable populations of this tick in the U.S.A.