The black spine-neck swamp turtle (Acanthochelys spixii), also commonly known as the spiny-neck turtle or Spix´s sideneck turtle, is a species of turtle in the family Chelidae. The species is endemic to South America, specially in the Southern Cone region.

Etymology: The specific name, spixii, is in honor of German biologist Johann Baptist von Spix.

Geographic range: A. spixii is found in Argentina, Brazil, Uruguay, and possibly Paraguay.