Centrorhynchus cf. amphibius, Das 1950 (Acanthocephala, Centrorhynchidae) in birds of prey from Pampa Biome, southern Brazil

Centrorhynchus Lühe, 1911 is a diverse genus of acanthocephalans parasitizing birds of prey worldwide, yet molecular data remain scarce for many species. The present study investigates the occurrence, morphology and phylogenetic position of Centrorhynchus cf. amphibius in raptors from the Pampa biome, southern Brazil. Specimens were recovered from the intestines of Strigiformes and Accipitriformes and examined morphologically, with emphasis on proboscis armature (oncotaxy). Partial sequences of the 18S and 28S rRNA genes were generated and analysed using Bayesian inference. Morphological characters were largely consistent with the original description of C. amphibius, although minor discrepancies and the absence of previous molecular data justified the use of the conferatum designation. Phylogenetic analyses placed C. cf. amphibius within Centrorhynchus, forming a well-supported clade with C. microcephalus, C. clitorideus and C. magnus. This study provides the first records of C. cf. amphibius in Athene cunicularia, Bubo virginianus, Megascops choliba, Heterospizias meridionalis and Rupornis magnirostris, as well as the first molecular data for this taxon. The species exhibited low host specificity and wide ecological dispersion in wetland ecosystems of southern Brazil. These findings expand the known geographical distribution of C. amphibius to the American continent and highlight the need for further integrative taxonomic studies to resolve species boundaries and life-cycle relationships within the genus.