Gill monogenean communities (Platyhelminthes, Monogenea, Dactylogyridae) of butterflyfishes from tropical Indo-West Pacific Islands

<jats:title>SUMMARY</jats:title><jats:p>We studied the monogenean communities of 34 species of butterflyfish from the tropical Indo-West Pacific, identifying 13 dactylogyrid species (including two species that are presently undescribed). Monogenean assemblages differed significantly between host species in terms of taxonomic structure, intensity and prevalence. Parasite richness ranged from 0 (<jats:italic>Chaetodon lunulatus</jats:italic>) to 11 (<jats:italic>C. auriga, C. citrinellus</jats:italic> and <jats:italic>C. lunula</jats:italic>). Host specificity varied between the dactylogyrids species, being found on 2–29 of the 34 chaetodontid species examined. Sympatric butterflyfish species were typically parasitized by different combinations of dactylogyrid species, suggesting the existence of complex host–parasite interactions. We identified six clusters of butterflyfish species based on the similarities of their dactylogyrid communities. Dactylogyrid richness and diversity were not related to host size, diet specialization, depth range or phylogeny of butterflyfish species. However, there was a weak positive correlation between monogenean richness and diversity and host geographical range. Most communities of dactylogyrids were dominated by <jats:italic>Haliotrema aurigae</jats:italic> and <jats:italic>H. angelopterum</jats:italic>, indicating the importance of the genus <jats:italic>Haliotrema</jats:italic> in shaping monogenean communities of butterflyfishes. This study casts light on the structure of the monogenean communities of butterflyfishes, suggesting that the diversity and complexity of community structures arises from a combination of host species-specific parameters.</jats:p>