Abstract
A new species of leucothoid amphipod, Leucothoe nagatai, is described from Japanese coastal waters. This new species was found in the branchial cavities of two solitary ascidians, Styela plicata and Halocynthia roretzi. Among several allied species, the new species is most similar to L. brevidigitata in the small and narrow incisor of mandible, but differs from it in several important features.
