In this study the finding of the sponge Clathria (Clathria) unica in coastal waters of Mar del Plata city (38°14′24″S, 57°27′30″W), Argentina, at the formation called ‘Banco de Afuera’, is reported. This record constitutes the northernmost record of the species, which was known until the present study only from its type locality in San Antonio Oeste, Río Negro province. Additionally, the bathymetric range of the species is updated from intertidal to 20 m. Other two common sponge species, Cliona aff. celata and Spongia (Spongia) magellanica, were also recorded in this environment for the first time.
