Morphology, ecology, and reproduction of a new Polydora species from the east coast of North America (Polychaeta : Spionidae)

A new spionid polychaete species, Polydora neocaeca, is described from inte rtidal and shallow subtidal areas in Rhode Island on the east coast of Nort h America. Adults bore into shells of living gastropods, gastropod shells o ccupied by hermit crabs, and bivalve shell fragments. Females deposit 13-24 egg capsules joined in a string from June-November. Each egg capsule is at tached by two stalks to the inside wall of the burrow and contains 8-47 egg s, for a mean of 481 eggs per brood. The eggs have an average diameter of 1 16 mu m. Development occurs within the egg capsules until the 3-segment sta ge at which time planktotrophic larvae are released. A series of adult morp hological characters was examined and found to vary extensively in body pig mentation but less so in palp pigmentation, prostomium shape, presence of n eurosetae and notosetae of the fifth segment, and caruncle length. Polydora neocaeca belongs to the Polydora ciliata/websteri species group and is cha racterized by palps crossed by black bars, incised prostomium, and caruncle extending up to the middle of segment 4. Polydora species with banded palp s are reviewed and systematic revision of P. agassizi Claparede, 1869 and P . limicola sensu Hartman (1961) is proposed.