 Isotelus was named by Dekay 1824. Its type is Isotelus gigas.It was reranked as Asaphus Isotelus by Owen 1852.It was assigned to Asaphus by Owen 1852; to Asaphinae by Phleger 1933 and Whittington 1941; to Isotelinae by Henningsmoen 1960 and Owen 1981; to Asaphida by Sepkoski 2002; and to Asaphidae by Jell and Adrain 2003 and Owens and Fortey 2009.I. aktchokensis, I. bradleyi, I. copenhagenensis, I. frognoensis, I. gigas type species, I. harrisi syn. I. platymarginatus, I. iowensis, I. kimmswickensis, I. maximus, I. megistos, I. parvirugosus, I. platyrhachis, I. skapaneidos, I. spurius, I. susae, I. violaensis, I. walcotti syn. I. planus1824 Isotelus Dekay1852 Asaphus Isotelus Owen1933 Isotelus Phleger, Jr. p. 181941 Isotelus Whittington p. 5121960 Isotelus Henningsmoen1981 Isotelus Owen2002 Isotelus Sepkoski, Jr.2003 Isotelus Jell and Adrain p. 3892009 Isotelus Owens and Fortey 