Abstract
Cirratulidae from Mar del Plata (38ºS, 57ºW) are under revision. The city has an intertidal outfall, and several polychaetes are associated with both intertidal and subtidal communities in organically enriched areas. The present paper provides the first records of the cirratulid genera Protocirrineris and Aphelochaeta from Argentine waters: P. angelicollatio sp. nov. from intertidal areas and A. malefica sp. nov. from shallow subtidal areas. Living specimens of P. angelicollatio sp. nov. were observed and asexual reproduction and high regeneration rates have been observed.