Ribeiroia (/raɪˈbɪəriːə/) is a genus of trematode parasites that sequentially infect freshwater snails in the family Planorbidae (ramshorn snails) as first intermediate hosts, fish and larval amphibians as second intermediate hosts, and birds and mammals as definitive hosts (see ). In North America, infection by Ribeiroia has been linked to amphibians with limb malformations. The connection between parasitic infection and limb malformations has generated questions about (a) whether parasite-induced malformations in amphibians are increasing (see ), and (b) the consequences of such abnormalities for amphibian population conservation (see ).