New host report of Reighardia sternae in the pomarine jaeger (Stercorarius pomarinus; charadriiformes: stercorariidae) stranded in Northeastern Brazil.

The pomarine jaeger Stercorarius pomarinus (Charadriiformes: Stercorariidae) is a migratory seabird with rare occurrence in the western South Atlantic, including the Brazilian coast. Despite its wide distribution in the Northern Hemisphere, parasitological records for this species are scarce and sporadic. The present study reports the first record of Reighardia sternae (Pentastomida: Reighardiidae) parasitizing the pomarine jaeger in Brazil. In April 2025, an adult female specimen of pomarine jaeger was rescued on the coast of the state of Sergipe, northeastern Brazil, and admitted for rehabilitation, dying six days after rescue. During necropsy, two pentastomids were found in the trachea. The parasites were identified based on diagnostic morphological characteristics, including a buccal region shaped as an elliptical opening, internally supported by a Y-shaped chitinous ring, the presence of simple hooks - each associated with a horseshoe-shaped chitinous bar with bifurcated terminal ends, and poorly evident, obscured genital organs. Histopathological findings suggested disseminated circulatory disturbance and early metabolic and nutritional alterations, with no conclusive evidence allowing the establishment of a direct causal relationship between the parasitic infection and death. This record increases the number of bird species recognized as hosts of R. sternae to 18. The results highlight the importance of parasitological investigations in seabirds, particularly in Neotropical regions, where parasite diversity remains underdocumented.