A new species of <i>Trichobilharzia</i> (Digenea: Schistosomatidae) from <i>Mareca sibilatrix</i> (Aves: Anatidae), an endemic South American duck

Avian schistosomatids are blood flukes parasitizing a wide spectrum of aquatic birds. However, its research in the Neotropics is ongoing with several putative new <i>taxa</i> pending description. Although waterfowl represent the most important avian hosts for these flukes, only a small proportion of these birds have been assessed for schistosomatids. This study aimed to describe avian schistosomatids from two native ducks from the Southern Cone of South America. A total of 24 Chiloe wigeon (<i>Mareca sibilatrix</i>) and three Cinnamon teals (<i>Spatula cyanoptera</i>) from different localities in Chile and Argentina were dissected to retrieve schistosomatids. The retrieved worms were described through an integrative approach considering morphology (staining and SEM) and molecular tools (PCR: <i>COI</i>, <i>28S</i> rRNA genes). The new schistosomatid: <i>Trichobilharzia kulfu</i> sp. nov. was recovered from the viscera of Chiloe wigeon. It was closely related to other undescribed <i>Trichobilharzia</i> taxa from the United States, also from <i>Mareca</i> ducks. The new species was morphologically and molecularly different from other <i>Trichobilharzia</i> species, and it was included in the clade Q. In addition, SEM imaging proved to be an important tool to describe unnoticed traits on the tegument of worms. This new species represents the second <i>Trichobilharzia</i> taxon from the Neotropics described through an integrative approach. Furthermore, the Cinnamon teals harboured <i>Trichobilharzia querquedulae.</i> Considering there are several avian schistosomatids described only through morphological or molecular tools, there is a clear need to include a comprehensive approach in the description of avian schistosomatids, considering the remarkable richness of schistosomatids in Neotropics.