S. piscinarium was originally classified as a species of Lutra. The giant otter of South America is considered the closest living relative of this genus.[3]
^Prevosti, Francisco J.; Ferrero, Brenda S. (2008). "A Pleistocene giant river otter from Argentina: remarks on the fossil record and phylogenetic analysis". Journal of Vertebrate Paleontology. 28 (4): 1171–1181. Bibcode:2008JVPal..28.1171P. doi:10.1671/0272-4634-28.4.1171. hdl:11336/80190.