The psyllid genus Triozidus Li, 1994 stat. rev., sensu novo (Hemiptera: Psylloidea: Triozidae) in East Asia is redefined with the addition of two new species from Taiwan inducing galls on the leaflet petiolules of Eleutherococcus trifoliatus (Araliaceae).

The genus Triozidus Li, 1994 stat. rev., sensu novo has a complex history. Here we redefine the genus as a natural group with two new species from Taiwan, Triozidus burckhardti Liao & Percy sp. nov. from the southernmost peninsula, and Triozidus yangorum Liao & Percy sp. nov. from the central and northern mountain region. In addition, we redescribe the type species, Triozidus stackelbergi (Loginova, 1967) comb. nov. and Triozidusukogi (Shinji, 1940) comb. nov., and we propose new combinations for a further two species as follows: Triozidus ceratophorus (Li, 2005) comb. nov. and Triozidus eleutherococci (Konovalova, 1980) comb. nov.; all new combinations except the latter are transferred from Heterotrioza Dobreanu & Manolache, and T. eleutherococci from Trioza Foerster. All but one Triozidus species with confirmed host plants are known to produce enclosed galls on Eleutherococcus (Araliaceae): Triozidus stackelbergi produces round galls on the leaf surface of Eleutherococcus sessiliflorus or more variably on leaf petioles, flowers, fruits and twigs of E. divaricatus; T. ukogi produces spindle-shaped galls on the leaf petioles or petiolules of E. spinosus; and T. yangorum produces round galls on the petiolules of the compound leaves or leaf bases of Eleutherococcus trifoliatus; T. burckhardti appears to share the same host plant and similar galling biology as T. yangorum. The description of T. yangorum and redescriptions of T. stackelbergi and T. ukogi are based on adults and immatures, and the immatures of T. stackelbergi and T. ukogi are described for the first time. Additionally, we provide new host and distribution records for T. stackelbergi in Japan. We provide identification keys for both adults and immatures, DNA barcode data for four of the six species, and an annotated mitochondrial genome for T.yangorum.