Polydorid species (Polychaeta: Spionidae) in Japan, with descriptions of morphology, ecology and burrow structure. 1. Boring species

A total of 13 boring species of spionid polychaetes were extracted from 28 different calcareous substrata (i.e. mollusc shells, coralline algae and barnacle tests) from Japan. The spionids were: seven Polydora spp.: Polydora brevipalpa, P. websteri, P. curiosa, P. uncinata, P. aura, P. glycymerica, Polydora sp.; five Dipolydora spp.: Dipolydora concharum, D. bidentata, D. alborectalis, D. giardi, D. armata; and one Carazziella sp.: Carazziella reishi. All of them inhabited self-excavated burrows in living and/or migratory calcareous substrata and they were never found from soft sediments. Burrow structures were species-specific. The Polydora species basically excavated simple U-shaped burrows, while the Dipolydora species excavated more varied, distinct burrows. The boring activity seemed species-specific among polydorids. This study attempts to summarize and discuss the biological characteristics of these boring species inhabiting Japan. In addition, P. curiosa, P. glycymerica, Polydora sp., D. giardi and C. reishi are new to Japan.