Structure of parasite component communities of didelphid marsupials: insights from a comparative study.

The parasite fauna of the gray four-eyed opossum, Philander opossum (Linnaeus, 1758), and the common opossum, Didelphis marsupialis Linnaeus, 1758, in Camp du Tigre, French Guiana, is characterized. Nine species from the gastrointestinal system were recovered from both species, which shared 80% of their parasites. The parasite fauna comprised several monoxenous species (63%) and was dominated by Aspidodera raillieti Travassos, 1914, which exhibited high levels of prevalence and abundance in both communities. Only 2 species (Moennigia sp. and Spirura guianensis) had been recorded in other species of mammals. Both species richness and taxonomic composition at the level of component communities from this locality were compared against 11 communities present in the Virginia ( Didelphis virginiana ), white-bellied (Didelphis albiventris), and common opossum from Argentina, Brazil, Mexico, and the United States. Neither host phylogeny nor taxonomy accounted for statistical differences in species richness. There was no statistical difference among species richness values among the 9 localities studied. Taxonomic similarity was analyzed by means of the Jaccard's similarity index, including all, and only common species (occurring in prevalence >10%). The results suggest that sympatric species of marsupials share more species of parasites than parasite communities occurring in conspecific marsupials from different localities. As a consequence, taxonomic composition of these parasite communities varied depending on the locality. Probably, marsupials of the monophyletic Didelphini offer the same compatibility toward their parasites, by presenting them with similar habitats. Subtle differences in lifestyles of the marsupials may determine the chance of encounter between the symbionts and prevent some parasites from completing their life cycles. Further and more rigorous tests are necessary to determine the roles of encounter and compatibility filters, as well as the role of chance, in the structuring of parasite communities in marsupials.