Phylogenetic position of the acoel Oxyposthia praedator (Xenacoelomorpha: Convolutidae)

Abstract

Eighteen named species of acoels have been reported from Japanese waters, though none from Hokkaido. Our faunal survey in Oshoro Bay, Hokkaido, revealed the presence of Oxyposthia praedator Ivanov, 1952, originally described from material collected in southwestern Sakhalin and subsequently recorded in the Gulf of Peter the Great. Molecular phylogenetic analysis based on the cytochrome c oxidase subunit I, 18S rRNA, and 28S rRNA genes indicates that O. praedator belongs to the family Convolutidae. However, its sister taxon could not be identified with high confidence. This is the first species-level identification of Acoela from Hokkaido and a new record of the species in Japan.