Phorodon japonensis Takahashi (1965)

was described as a subspecies of P. humuli . The species is holocyclic, overwintering on Prunus mume Siebold & Zucc. It differs from P. humuli in having a shorter projection on the frontal tubercle of the aptera. The ratio of the lengths of the ultimate rostral segment and the second hind tarsal segment is larger in P. japonensis than in P. humuli . This aphid was treated at the species level by Zhang et al. (1999) and Blackman and Eastop (2006).