Background: The epidemiology of schistosomiasis in Senegal is very dynamic. While Schistosoma mansoni was the dominant parasite at the onset of the epidemic, the urinary species, S. haematobium, was mostly absent. Nowadays this pattern is almost completely reversed. In addition, molecular analyses revealed that children were infected with hybrid between S. haematobium and S. bovis, the latter being a livestock parasite. This species uses a different snail host to complete its life cycle. It is not known, however, which snail species is used by the hybrid. If it is able to use the same host as S. bovis, it could explain the rise in urinary schistosomiasis because this snail species is very abundant across Northern Senegal. To test this we sampled the main snail intermediate host species in the lower and middle delta of the Senegal River Basin (2012-2014). We barcoded the snails by sequencing or RFLP analysis of partial cytochrome c oxidase 1 (cox1) and tested each snail for s! chistosome infection using a diagnostic PCR. Results: The most dominant snail species was Bulinus truncatus, the host of S. bovis, followed by B. globosus, the main host of S. haematobium. The former was exclusively infected by pure S. bovis parasites, with the exception of the snails from the middle delta, while the latter was infected with S. haematobium and with hybrid parasites. The distribution of both species was heterogeneous along the river basin, as was the distribution of the hybrids in children obtained during a previous study. Significance: These results show that B. globosus is the most important snail species for human schistosomiasis in the lower delta. However, B. truncatus of the middle delta appears susceptible to both human and veterinary schistosome species. If this species manages to colonize the lower delta, it might strongly impact schistosomiasis epidemiology.