During the examination of 913 fish specimens belonging to four families in the Campeche Bank (Gulf of Mexico), 23 gill ectoparasitic monogenean species were found, which belong to three families: Dactylogyridae, Microcotylidae and Diclidophoridae. The speciesEuryhaliotremaamydrum,E.carbuncularium,E.dunlapae,E.fajeravilae,E.fastigatum,E.longibaculum,E.paracanthi,E.tubocirrus,Haliotrematoidescornigerum,H.gracilihamus,H.heteracantha,H.longihamus,H.magnigastrohamus,H.striatohamus,Hamatopedunculariabagre,Neotetraonchusbravohollisae, andN.felis(all Dactylogyridae) were found on the hostsLutjanussynagris,L.griseus,Ariopsisfelis,Bagremarinus,Archosargusrhomboidalis, andHaemulonplumieri. Additionally,Microcotylearchosargi,Microcotylesp., andMicrocotyloidesincisa(all Microcotylidae) were found onL.griseusandA.rhomboidalis; finally,Choricotylesp. 1,Choricotylesp. 2, andChoricotylesp. 3 (all Diclidophoridae) were found onH.plumieri. The prevalence, abundance, mean intensity of infection, and supplementary taxonomic revisions for all monogeneans found are provided. Partial sequences of the 28S rRNA gene were also obtained for monogeneans of ariid, sparid, and haemulid host fishes to explore their systematic position within the Monogenea. New locality and host records for some previously described species ofEuryhaliotrema,Hamatopeduncularia,Microcotyle, andChoricotylefrom lutjanid, ariid, sparid, and haemulid hosts were reported. The present study adds evidence supporting the interoceanic occurrence of the same monogenean species (on lutjanids) on the west-east Atlantic and Pacific Oceans (= amphiamerican species). As previously suggested, there are at least, two possibilities to explain that parasite distribution: differentiation of morphological features in these monogeneans have resulted in only slight to insignificant morphological changes developing over the extended period of 3.2 mya (when the Isthmus of Panama was closing) and/or speciation is only evident at molecular level.
