Laetmonice iocasica sp.nov.,a new polychaete species(Annelida:Aphroditidae)from seamounts in the tropical Western Pacific,with remarks on L.producta Grube,1877

Laetmonice Kinberg,1856 is a remarkable genus characterized by having harpoon notochaetae in the polychaete family Aphroditidae.We describe a new species of Laetmonice,Laetmonice iocasica sp.nov.,found from seamounts on the Caroline Ridge in the tropical Western Pacific.The new species is readily distinguished from congeners,particularly those distributed in the Indo-Pacific Ocean by possessing45 segments with 18 pairs of elytra,and the tuberculated harpoon notochaetae in the elytrigerous segments,which are replaced by tuberculated notochaetae without recurved fangs on segments 4 and 5.Laetmonice iocasica sp.nov.is closely related to L.producta Grube,1877,but differs in both morphology and the genetic distance of the mitochondrial cytochrome oxidase subunit I(COI)sequences.Laetmonice producta Grube,1877 contained five varieties reported in various marine areas,which have been raised to species level.However,the records of L.producta from the Sagami B ay and Suruga B ay in Japan and in the south-eastern Australia remain obscure and probably represent a different species.The data indicate that L.producta,which was originally described from Kerguelen Islands in the Southern Ocean and later commonly found on the Antarctic shelf,is probably distributed only at high latitudes of the Southern Hemisphere.