Seven species of Euryhaliotrematoides n. gen. and 1 species of Aliatrema n. gen. (Monogenoidea; Dactylogyridae) are described and reported from the gills of 15 species of butterfly fishes (Chaetodontidae) from the coral reefs of Moorea (French Polynesia), Wallis (Wallis and Futuna), Heron and Lizard (Australia), Palau (Micronesia), and New Caledonia: Aliatrema cribbi n. sp. from Chaetodon auriga, Chaetodon lunula, Chaetodon trifasciatus, Chaetodon ulietensis, Chaetodon vagabundus, Forcipiger flavisissimus, and Heniochus chrysostomus; Euryhaliotrematoides annulocirrus n. comb. from C. auriga, C. lunula, and C. vagabundus; Euryhaliotrematoides aspistis n. sp. from C. auriga, Chaetodon citrinellus, C. lunula, Chaetodon reticulatus, C. ulietensis, and C. vagabundus; Euryhaliotrematoides berenguelae n. sp. from C. citrinellus, Chaetodon ornatissimus, and F. flavisissimus; Euryhaliotrematoides grandis n. comb. from C. auriga, C. citrinellus, Chaetodon ephippium, Chaetodon kleinii, Chaetodon lineolatus, C. lunula, C. ornatissimus, C. trifasciatus, C. vagabundus, and H. chrysostomus; Euryhaliotrematoides microphallus n. comb. from C. auriga, C. citrinellus, C. ephippium, C. kleinii, C. lunula, C. ornatissimus, C. reticulatus, Chaetodon trifascialis, C. trifasciatus, C. vagabundus, F. flavisissimus, and H. chrysostomus; Euryhaliotrematoides pirulum n. sp. from C. auriga, C. citrinellus, C. lunula, C. trifasciatus, and C. vagabundus; and Euryhaliotrematoides triangulovagina n. comb. from C. auriga, C. citrinellus, C. kleinii, C. lunula, C. ornatissimus, C. vagabundus, F. flavisissimus, H. chrysostomus, and Hemitaurichthys polylepis. All reports of previously described species ar