TL;DR: The genus Agagus is thought to be distinct from other trochid genera and to belong to the subfamily Trochinae, tribe Gibbulini.
Abstract: Agagus agagus Jousseaume, 1894, is redescribed and a lectotype is designated and figured Two species Gibbula townsendi Sowerby, 1895 and Gibbula perspectiva Sowerby, 1900, are shown to be junior synonyms A new species, Agagus stellamaris, is described from East Africa Observations on radula morphology and external anatomy are given The genus Agagus is thought to be distinct from other trochid genera and to belong to the subfamily Trochinae, tribe Gibbulini The holotype of Gibbula (Enida) perspectiva Sowerby, 1900, is figured