Recently specimens of the polychaete Marphysa sanguinea (Montagu, 1813) (Annelida: Eunicida: Eunicidae) were reported as an introduction to the Eastern Scheldt in southwestern Netherlands. In order to confirm the species identity, material was examined with SEM and compared with material from Devon near the type locality in Cornwall, UK. These studies confirmed that this was a new record of M. sanguinea, which can be distinguished from other Marphysa species by the pattern of the distribution of pectinate chaetae in posterior parapodia. This new record extends the known distribution of the species based on verified records, eastward along the English Channel. As the specimens from the Netherlands show additional variation, the species description of M. sanguinea is expanded, which will facilitate future identifications of this species and comparison with other members of the genus. ; Recently specimens of the polychaete Marphysa sanguinea (Montagu, 1813) (Annelida: Eunicida: Eunicidae) were reported as an introduction to the Eastern Scheldt in southwestern Netherlands. In order to confirm the species identity, material was examined with SEM and compared with material from Devon near the type locality in Cornwall, UK. These studies confirmed that this was a new record of M. sanguinea, which can be distinguished from other Marphysa species by the pattern of the distribution of pectinate chaetae in posterior parapodia. This new record extends the known distribution of the species based on verified records, eastward along the English Channel. As the specimens from the Netherlands show additional variation, the species description of M. sanguinea is expanded, which will facilitate future identifications of this species and comparison with other members of the genus.