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The systematic position of the fossil species referred toCalliotropisis currently under debate due to the striking resemblance between these forms with their extant counterparts in general shell morphology and ornament pattern. We propose two temporal subgenera ofCalliotropis:Calliotropis(Riselloidea) for Mesozoic species andCalliotropis(Calliotropis) for Cenozoic and Recent taxa. We also synonymize the families Eucyclidae and Calliotropidae, and redescribe the type genus of Eucylidae based on topotypic material ofE. obeliscusfrom Normandy. We argue that the generic nameAmberleyashould be restricted to its type speciesAmberleya bathonica. For the species that were traditionally included inAmberleya, we propose the new genusAmbercyclus, with its type speciesAmberleya orbignyana. The present paper also provides descriptions of threeCalliotropisspecies from the Early Jurassic marine deposits of Argentina. The occurrence ofCalliotropis(Riselloidea)keidelin. sp.,Calliotropis(Riselloidea) cf.C. (R.)keideliandCalliotropis(Riselloidea) sp. in the Jurassic of Chubut and Neuquén provinces represents a new record of the genus in Early Jurassic sediments of Argentina and South America. Moreover, two species ofAmbercyclusn. gen., such asAmbercyclus espinosusandAmbercyclus?isabelensisn. sp., are described from the same deposits.Eucyclus,Amberleya,Ambercyclus, andCalliotropisare included into Eucyclidae, which we consider to be a family of Seguenzioidea.

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