Monorchotrema

Mon·or·cho·tre·ma (mon-or″ko-treґmə) [mono- + Gr. orchis testicle + trēma aperture] a genus of flukes of the family Heterophyidae, found in birds and mammals in the Middle East and Taiwan, and characterized by having only a single testis. They have as invertebrate host an operculate snail, and as first vertebrate host an edible fish.