Ilyophis arx is an eel in the family Synaphobranchidae (cutthroat eels).[1] It was described by Catherine H. Robins in 1976.[2] It is a marine, deep water-dwelling eel which is known from the eastern Pacific and northeastern Atlantic Ocean. It dwells at a depth range of 1790mto3225mm (5,870feetto10,581feetm). Males can reach a maximum total length of 44.7cm (17.6inches).[1]