Reproduction and morphology of Polydorella (Polychaeta: Spionidae), including the description of a new species from the Philippines

A new spionid polychaete, Polydorella kamakamai, associated with sponges is described from the Philippines. Polydorella kamakamai is characterized by acicular neurosetae in segments 2–7, a fifth segment containing a ventral row of spines with digitiform bosses, and lack of branchiae. As in all members of the genus, P. kamakamai undergoes asexual reproduction via paratomy; the process of paratomy is examined through scanning electron and light microscopy. This species exhibits a growth zone following segment 10, leading to the production of stolon individuals budding from the stock individual; five or more individuals can thus be formed in a single chain. Paratomic division typically occurs in chains containing four to five individuals and as a result colonies are dominated by chains of two individuals. Sexual reproduction is documented for only the second time in the genus; P. kamakamai produces eggs in segments 13–15. Asexual reproduction and fine morphological structure of the ventral spines of the fifth segment are examined by SEM in P. dawydoffi and P. stolonifera. Polydorella dawydoffi is recorded for the first time from the Philippines and the Red Sea and these are compared to type specimens from Vietnam. The ventral spines of P. dawydoffi contain eight or nine rounded or pointed teeth along the apical end and a capillary extension not previously observed with light microscopy. Notes on feeding biology, parasitism by copepods, and a discussion of the evolutionary relationships of Polydorella and other polydorids are provided.