Helminths assemblage in two opossum's species, Didelphis albiventris and Didelphis aurita (Mammalia: Didelphimorphia), from the Atlantic Forest of Argentina.

In the Argentinian Atlantic Forest (AAF) of Misiones, opossums comprise 13% of the wild mammalian diversity. The white-eared opossum, Didelphis albiventris, and the southern black-eared opossum, D. aurita are sympatric marsupials, and the most frequent mammals in the northern Misiones. In this study, we describe the helminth assemblages from both D. albiventris and D. aurita in the northern AAF. We found a total of 15 species of helminths: 2 trematodes, 1 cestode, 11 nematodes and 1 acanthocephalan. The specific richness in D. albiventris was 12, while in D. aurita was it 13. Both opossum's species share 10 helminth species; D. albiventris presented Capillaria sp. 2 and Globocephalus marsupials, absent in D. aurita; while D. aurita presented Trichuris didelphis, Capillaria sp. 1, and Travassostrongylus orloffi, absent in D. albiventris. Cruzia tentaculata registered the highest prevalence in both opossum species. Seven out of the 12 helminth species identified in D. albiventris have an indirect life cycle. Similarly, in D. aurita, 5 out of 13 helminth species exhibit an indirect life cycle. This suggests that nearly half of the assemblage of helminth in both opossum species need an intermediate host acquired through the diet. We also present new records for Argentina including Trichuris minuta, G. marsupialis, Viannaia viannai, T. orloffi and T. callis. This is the first time the helminth assemblage has been described for D. aurita in Argentina.