Cymatium was named by Röding (1798) [Sepkoski's age data: T Eo-m-l R Sepkoski's reference number: 125]. It is extant.

It was reranked as Triton (Cymatium) by Mörch (1877); it was reranked as Tritonium (Cymatium) by Gabb (1881).

It was assigned to Triton by Mörch (1877); to Tritonium by Gabb (1881); to Cymatiidae by Oostingh (1935), Turner (1938), Gardner (1947), MacNeil (1960), Addicott (1970), Ladd (1977), Ladd (1982), Squires (1983), Squires (1984), Frassinetti and Covacevich (1995); to Neotaenioglossa by Sepkoski (2002); to Cymatiinae by Wilson (1993), Beu (2005); and to Ranellidae by Todd (2001), Beu (2010).