Yatsu/Japan/Tokyo Bay (Imajima 1990, cited by Rice and Levin 1998), named as a a new subspecies, Streblospio benedicti japonica. The taxonomic position of the form is not clear- it could be a sibling species.
Yatsu/Japan/Tokyo Bay (Imajima 1990, cited by Rice and Levin 1998) Imajima M 1990. Spionidae (Annelida, Polychaeta) from Japan 5. The genera Streblospio and Dispio. Bulletin of the National Science Museum Series A Zoology. 1990; 16(4): 155-163