The present paper deals with new species of the genus Euchromadora DE MAN and Steineridora INGLIS as the second report of the taxonomic work of free-living marine
nematodes from Hokkaido. Although three species belonging to the genus Euchromadora DE MAN were recorded from Japan; i.e., E archaica STEINER et HOPPLI, 1926 from
Joshi Island near Kobe, E. amokurae (DITLEYSEN, 1921) and E.tokiokai WIESER, 1955 from Shirahama, the former two species have already been referred to the genus Steineridora and Graphonema INGLIS respectively by INGLIS (1969). The present two new species are,
therefore, the second member of each genus in Japan.
Specimens were collected on Sargassum confusum AGARDH in Oshoro Bay on the Japan Sea coast of Hokkaido and all the specimens examined are deposited in the Zoological
Institute, Faculty of Science, Hokkaido University.