Polydora and Related Genera Associated with Hermit Crabs from the Indo-West Pacific (Polychaeta: Spionidae), with Descriptions of Two New Species and a Second Polydorid Egg Predator of Hermit Crabs

Abstract

Polydora and related genera associated with hermit crabs from shallow subtidal coral reef areas of the Indo-West Pacific are described. Over 2000 hermit crabs were collected from localities in the Philippines and Indonesia between July 1997 and April 1999. In total, 10 species of polychaetes among five genera (Boccardia, Carazziella, Dipolydora, Polydora, and Tripolydora) were identified and described. Adult morphology of these species was investigated with light microscopy and scanning electron microscopy. The study includes the description of two new Polydora species, including the second known polydorid egg predator of hermit crabs. Six of the species burrow into calcareous substrata, living in burrows within live or dead gastropod shells or coralline algae attached to shells. Two species were found in mud tubes within crevices of gastropod shells inhabited by hermit crabs. The zoogeography and biodiversity of polydorids from the West Pacific are discussed. The diversity of polydorids from the Philippines is comparable with that of other central Pacific and Indo-West Pacific islands, but it is lower than that in areas of the North and Southwest Pacific; lower diversity probably reflects disparity in sampling efforts between these regions. A key to the Philippine polydorids is provided.