This study evaluated the diversity of the genus Eurydice on sandy beaches in South Africa by analysis of morphological as well as genetic data. Type specimens of the three Eurydice species currently known from South Africa, E. longicornis, E. kensleyi and E. barnardi were obtained from the Museum für Naturkunde in Berlin and the Iziko Museum in Cape Town, South Africa. These specimens were studied in order to become familiar with their morphology. Eurydice individuals obtained from 30 sites spanning the South African coast, from Port Nolloth on the north-west coast to Bhanga Nek on the north-east coast were then examined. The two species E. kensleyi and E. barnardi, as well as four new morphospecies (A, B, C and D) were discriminated from these individuals by suites of morphological character types. Morphospecies A, B, C and D were therefore delimited according to the Phenetic Species Concept. None of the Eurydice individuals examined exhibited the same suite of characters as E. longicornis. Molecular sequences of two mitochondrial markers, cytochrome c oxidase 1 and 16S rRNA were analysed using both distance- and monophyly based methods. Uncorrected p-distances, a Minimum Spanning Haplotype Network and Maximum Likelihood phylogenetic trees were investigated to determine genetic diversity and phylogenetic relationships in the six Eurydice morphospecies. Results from the genetic analysis made it possible to delimit morphospecies A B, C and D as phylospecies A, B, C and D according to the Phylogenetic Species Concept, thereby validating the species status of four new Eurydice species, provisionally called Eurydice A, Eurydice B, Eurydice C and Eurydice D. This increases the total number of Eurydice species from South Africa to seven, of which six form part of the macrofauna of sandy beaches. The outcomes of this study represent an important step in the resolution of the taxonomy of the genus Eurydice in South Africa and enhance current knowledge of the biodiversity of sandy beach macrofauna, thus facilitating better-informed decisions on conservation policies and management to the benefit of conservation of biodiversity on sandy beaches in South Africa.