Four new species of , , and (Cirratuliformia, Annelida) in Japanese waters, with notes on their phylogenetic position.

Four new species of annelids, sp. nov., sp. nov., sp. nov., and sp. nov., are described based on specimens collected from Japanese waters. sp. nov. inhabits the interstitial environment and can be distinguished from the other congeners by the following features: () total of 16 chaetigers, () chaetigers 1-3 with stout hooks, () minute body (approximately 1 mm in length), () all parapodia with the same number of chaetae (two notochaetae; two neurochaetae), and () presence of dorsal and ventral papillae. sp. nov. lives under intertidal stones and can be distinguished from other congeners by having pectinate neurochaetae. sp. nov. inhabits the interstitial environment and can be distinguished from other congeners by: () absence of annulation on the peristomium and achaetous segment and () presence of a heart body in chaetigers 4-5. sp. nov. inhabits whale bones and can be distinguished from other congeners by the following features: () presence of a heart body in chaetigers 9-14, () presence of capillary neurochaetae on chaetiger 1, and () presence of simple curved spines. A phylogenetic tree based on partial sequences of cytochrome oxidase subunit I and 16S rRNA from the new species and other cirratulid worms showed that is included in Cirratuliformia. This is the first record of and from Japanese waters.