New record of the monostiliferous hoplonemertean Gurjanovella littoralis Uschakov, 1926 from Japan (Nemertea, Hoplonemertea, Monostilifera)

A single specimen of a monostiliferous hoplonemertean, collected from a depth of 25 m in Akkeshi Bay, northern Japan, represents the first record of Gurjanovella littoralis Uschakov, 1926 from the Northwest Pacific. The species has been known only from the type locality, White Sea, Russia, although some planktonic larvae from Oregon, USA, and a juvenile from the Sea of Okhotsk have been identified as a member of the genus by molecular sequence data. Our specimen differs from a topotype from the White Sea by 2.9% of uncorrected p-distance and 3.0% of K2P in terms of partial 658-bp sequence of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Our COI phylogenetic tree indicates that each of the larvae from Oregon and the Sea of Okhotsk belongs in Gurjanovella but represents a different species from G. littoralis.