Eleutherocentrus williamsi was named by Ross (1951) [Paratypes: YPM 18032-3.]. Its type specimen is YPM 18031, a cephalon/head (cranidium), and it is a 3D body fossil. Its type locality is Locality 13, Round Hill, Zone "J", which is in a Blackhillsian shallow subtidal limestone/chert in the Garden City Formation of Utah. It is the type species of Goniotelina.

It was recombined as Goniotelina williamsi by Whittington (1953), Neuman and Bruton (1974); it was recombined as Acidiphorus williamsi by Brett and Westrop (1996).