Hydromedusa, commonly known as the South American snake-necked turtles, is a genus of turtles in the family Chelidae. They are quite closely related to the South American side-necked swamp turtles (Acanthochelys) and the snake-necked turtles of the Australian-Melanesian region (Chelodina), but less closely to the spine-necked river turtles of South America (Podocnemididae) which belong to a more modern lineage of Pleurodira.

...