Abstract
As part of a study on Marphysa de Quatrefages, 1865 from the Grand Caribbean, three species regarded as junior synonyms of M. sanguinea (Montagu, 1913) were studied to clarify their taxonomic status. The examination of type and additional materials collected in the southern Gulf of Mexico and the Mexican Caribbean regions, allowed us to clarify that M. acicularum Webster, 1884, M. nobilis Treadwell, 1917 and M. viridis Treadwell, 1917 are distinct species. Therefore, the three species were redescribed and some important morphological features such as maxillary apparatus, shape of parapodial lobes, shape of ventral cirri and pectinate chaetae, among others, were described and evaluated. Furthermore, we consider that previous records of M. sanguinea for the Grand Caribbean are doubtful and it is necessary to reassess those specimens to clarify their taxonomic identity.