Baer studied the type material of both T. axenos and T. brasiliensis, so he described and illustrated T. axenos better. and in the same work synonymized T. brasiliensis with the latter.More recently, Perez-Gonzalez described Temnocephala bresslaui, pointing out a few diagnostic characters in order to separate it from T. axenos, but some of these characters have been proven to have no taxonomic value.Finally, Dioni synonymized T. bresslaui with T. axenos in the same work in which he described T. talicei.