Maritrema is a genus of flukes in the family Microphallidae, although some have suggested its placement in the separate family Maritrematidae. It was first described by Nikoll in 1907 from birds in Britain. Species of the genus usually infect birds, but several have switched hosts and are found in mammals, such as the marsh rice rat. Several species use the fiddler crab Uca pigilator as an intermediate host. Species include: