Unveiling helminth diversity in Scinax Wagler, 1830 (Anura: Hylidae): New records from S. x-signatus (Spix, 1824) in the Caatinga domain, Brazil, and an overview of South America.

Amphibian helminth diversity remains poorly documented in semiarid environments, despite its relevance for understanding host-parasite interactions and biogeographical patterns. We investigated the helminth community of the hylid frog Scinax x-signatus from a Caatinga remnant in Petrolina (Pernambuco, Brazil) and reviewed the current state of knowledge on helminth infecting South American Scinax species. Twenty-five S. x-signatus (11 adult females, 9 adult males and 5 juveniles) were examined; of these, 13 specimens (52%) harboured at least 1 helminth taxon, with infracommunity richness ranging from 1 to 7 taxa. We identified four nematodes (Oswaldocruzia sp., Oxyascaris caudacutus, Oxysomatium sp., Rhabdias sp.), two digeneans (adults of Catadiscus sp. and metacercariae of Neodiplostomum sp., and cystacanths of an acanthocephalan (Centrorhynchus sp.). Oxyascaris caudacutus was the most prevalent taxon (20%) and exhibited the highest mean intensity (4.0 ± 2.77). Four taxa (Oswaldocruzia sp., O. caudacutus, Oxysomatium sp. and Catadiscus sp.) represent new host records for S. x-signatus. Our literature review identified 45 publications from 1940 to 2026 and showed that helminth have been recorded for only 13 South American Scinax species, comprising 78 taxa in total (46 Nematoda, 20 Trematoda, 8 Acanthocephala and 4 Cestoda). Records are strongly geographically biased, being restricted to five countries (Brazil, Argentina, Peru, Paraguay, and Ecuador), and most taxa remain identified only to genus or higher taxonomic levels. Our results expand knowledge of Caatinga amphibian parasites and reinforce the need for integrative surveys to better estimate helminth diversity across the South American continent.