For the “Sagitta serratodentata-group”, synonymy, morphology and biometrical data are given of S. serratodentata, S. tasmanica and S. pacifica. S. serratodentata is divided into two subspecies, S. serratodentata serratodentata and S. serratodentata atlantica. The zoogeography of all six taxa of the “S. serratodentata-group” is discussed.