Nipponaphis species (Aphididae: Hormaphidinae) that form green galls on Distylium racemosum in Japan

Some species of the aphid genus Nipponaphis (Nipponaphidini) form green, globular or fig-shaped galls on the evergreen Distylium racemosum, their primary host. Molecular phylogenetic analyses of aphid samples collected from both their galls and secondary hosts indicated the occurrence of four species in Japan: N. distychii, N. distyliicola, N. loochooensis and N. machilicola. The four species could also be discriminated from one another in morphology. The name N. litseae turned out to be a junior synonym of N. distychii. Galls formed by N. machilicola are reported for the first time in this paper. The life cycles of the four species are briefly reviewed.