New species of(Trematoda: Diplostomidae) from Argentine Patagonian birds: morphological and molecular characterisation.

Abstract

This study describes two new species of(Trematoda: Diplostomidae) and reports a new lineage parasitising birds in Northwestern Patagonia, Argentina, based on morphological and molecular evidence. Specimens were recovered from the intestines of,,, andbetween 2001 and 2025. Morphological analyses revealed that the new taxa, herein namedn. sp., andn. sp., and the unnamed speciessp. 1 show differences mainly in body segment ratio, sucker size, and vitelline gland distribution. This work contributes 14 new sequences to this genus. Phylogenetic analyses of nuclear (28S rDNA) and mitochondrial () sequences placedn. sp. within a clade comprisingand;sp. 1 clustered withand, among others, confirming the existence of two well-supportedlineages: the first is restricted to avian hosts, whereas the second includes birds and mammals. These results provide the first record of species of the genusin Patagonia, and the first molecular sequences for species of this genus in Argentina, thus expanding the known diversity and distribution of the genus in South America. The integrative approach supports the need for taxonomic revision of the genus