Tristoma /(trĭs"tō̇*mȧ)/

Tris·to·ma

Tristoma

n.
  1. Any one of numerous species of trematode worms belonging to Tristoma and allied genera having a large posterior sucker and two small anterior ones. They usually have broad, thin, and disklike bodies, and are parasite on the gills and skin of fishes. (Zool.)