Reproduction and larval development ofPolydorafrom Northern New England (Polychaeta: spionidae)

The reproduction, larval development and seasonal occurrence of planktonic larvae of eight species of Polydora from Maine are described. The species are: Polydora ligni, P. websteri, P. aggregata, P. commensalis, P. socialis, P. concharum, P. quadrilobata and P. caulleryi. The first seven named were reared from egg capsules and plankton isolates, while P. caulleryi larvae were only obtained from plankton isolates. A key to the polydorid larvae of New England is given. Polydora concharum and P. quadrilobata brood their larvae during the winter and possess the largest eggs encountered in this study. The remaining species brood their larvae in spring and summer and have smaller eggs. Polydora quadrilobata was found to exhibit two types of development in different populations during the same breeding season. In the first type of development (1), the larvae feed on unfertilized nurse eggs and have only a short pelagic life. In the second type of development (II), there are no nurse eggs and the larvae have a long pelagic life. It is suggested that two sibling species may be involved.