First record of Neoprosthenorchis sp. infecting cougars (Puma concolor) in South America, with possible pathogenic effects on their gastrointestinal tract.

Currently, the genus Neoprosthenorchis consists of a single acanthocephalan species, previously found only in bobcats in the United States. Literature on acanthocephalans infecting wild felids is limited, and Neoprosthenorchis species have not been previously recorded in cougars (Puma concolor). This study documents the presence of Neoprosthenorchis sp. in two free-ranging cougars from the Brazilian Cerrado biome. In August 2023 and January 2025, two cougar carcasses were necropsied, revealing acanthocephalan parasites attached to the mucosa of the large intestine, associated with a focal, well-defined ulcer. Detailed morphological examination confirmed the genus as Neoprosthenorchis. Histopathological analysis revealed focal, extensive, chronic, moderate, ulcerative, and fibrotic enteritis, containing structures consistent with an acanthocephalan parasite. Molecular characterization using 28S rRNA and cytochrome c oxidase subunit 1 (cox1) gene sequences provided the first molecular data for Neoprosthenorchis, contributing new phylogenetic information on the group. These findings document the first occurrence of Neoprosthenorchis in South America, expand our understanding of the hosts of these parasites, and provide evidence for a probable new species of Neoprosthenorchis.