Diopatra nishii, a new brooding species of Onuphidae (Annelida) from Japan

A small tubeworm, Diopatra nishii, is newly described from the shallow waters of Boso Peninsula and Izu Peninsula, as the second Japanese species of this genus. It differs from D. sugokai, a common baitworm in Japan, by its much smaller size, single rather than double postchaetal lobes on the modified parapodia and direct development in the parental tube rather than broadcast spawning. Juveniles of two different stages of the new species were found in a brood sac in the parental tube; these and recently settled juveniles are described.