Abstract Urban parks are not only important for the wellbeing of the human population, but are also widely considered to be potentially important sites for the conservation of biodiversity. However, they may offer risk parasitic infections, such as schistosomiasis and fascioliasis, which are both transmitted by freshwater snails. The present study investigated the occurrence of freshwater gastropods in urban parks of the Brazilian city of Rio de Janeiro, and their possible infection by helminths of medical-veterinary importance. Gastropods were collected from six parks (2021 - 2022) and examined for the presence of larval helminths. In all, 12 gastropod species from different families were collected: Ampullariidae, Assimineidae, Burnupidae, Lymnaeidae, Physidae, Planorbidae, Succineidae, and Thiaridae. The parasitological examination revealed cercaria of three types in five snail species, with the Pleurolophocerca cercariae type in Melanoides tuberculata (the most abundant species), Echinostoma cercariae in Physella acuta and Pomacea maculata, and Virgulate cercariae, in Pomacea sp. and Pomacea maculata. None of the Biomphalaria tenagophila and Pseudosuccinea columella (the most frequent species) specimens were parasitized by Schistosoma mansoni or Fasciola hepatica, respectively. Even so, some parks may represent a considerable potential risk for transmission of both Schistosoma mansoni and Fasciola hepatica, given the presence of these gastropod vectors and the frequent contact of visitors with the waterbodies. population biodiversity However infections fascioliasis snails Janeiro medicalveterinary medical veterinary importance 2021 (202 2022 all 1 Ampullariidae Assimineidae Burnupidae Lymnaeidae Physidae Planorbidae Succineidae Thiaridae , maculata sp hepatica respectively so waterbodies 202 (20 20 (2 2 (

Abstract Biomphalaria straminea is one of the three snails that act as the intermediate hosts of Schistosoma mansoni and is responsible for maintaining high rates of schistosomiasis in some areas of northeastern Brazil. The principal morphological characteristic of B. straminea is the marked vaginal wrinkling, although it is also present in congeneric species, a group known as the B. straminea complex. Based on the morphological and molecular analyses, we investigated the intraspecific variation of B. straminea. The specimens were obtained from 10 sites in Brazil, and the shells were analyzed, as well as 16 morphological structures of the reproductive system. The COI and ITS2 sequences were used for phylogenetic analysis, genetic divergence, and haplotype network (COI). We observed a large intraspecific variation in the morphological structures examined. The genetic divergence also demonstrated significant intraspecific variability in B. straminea: 0–3% in ITS2 sequences, and 0–6% in COI sequences. Analysis of the distribution of COI haplotypes recovered 16 haplotypes and haplotype diversity of 0.9088. These results indicate phenotypic variability that is not constrained to a locality or strictly controlled genetically by B. straminea, which may have driven a misidentified of these species. Brazil B wrinkling species complex analyses 1 analyzed system ITS analysis COI. . (COI) examined 03 0 3 0–3 06 6 0–6 09088 9088 0.9088 (COI 0– 0908 908 0.908 090 90 0.90 09 9 0.9 0.