This work is based upon a collection of Annelida Polychaeta assembled from the Mediterranean Coast of Israel during an ecological experiment on fouling. The present paper describes a new species of spionid, Prionospio salzi sp.nov. Some morphological and biological peculiarities lead to the conclusion that all specimens of P.salzi are old larvae. The systematic position of this species within the large genus Prionospio is considered. [NOT CONTROLLED OCR]