During the summer of 1964 studies were conducted on spionid polychaete larvae taken from plankton hauls at Morro Bay, California. Conspicuous larvae of a certain polydorid metamorphosed in the laboratory. They were first identified as Polydora hamata Webster which is known from the Atlantic and Gulf coasts of the United States but not the Pacific coast. These young worms (up to 34 segments) possessed branchiae on segments 7 to 12 (characteristic of the genus Polydora), posterior notopodial hooks, and small terminal protuberances on the pygidium (similar to pi. IX, fig. 118 of Webster, 1879a). With continued growth of the organism small branchiae became evident on segments 2, 3, and 6 which indicated the worms belonged to the genus Boccardia and had the characteristics of B. uncata Berkeley, a well-known Pacific species. Information gained from a subsequent examination of preserved adults of P. hamata and B. uncata from the Atlantic, Gulf, and Pacific coasts of the United States and P. uncatiformis Monro from Uruguay has necessitated the following taxonomic revision.
Polydora hamata Webster is herein transferred to the closely related genus Boccardia. Boccardia uncata Berkeley and Polydora uncatiformis Monro are herein placed in synonymy with Boccardia hamata (Webster), new combination. Further support for this revision follows a discussion of the adult morphology and ecology of B. hamata. The larval development will be presented in a later paper.