The oldest Naibiomorpha: new fossil from NW China with implications for their early evolution

The early morphology and evolution of Naibiomorpha, an extinct infraorder of Sternorrhyncha, remain poorly understood due to scarce fossil material. Herein, we report the oldest known representative of this infraorder: a new specimen of Dracaphis angustata from the Tongchuan Formation (Ladinian, Middle Triassic) in Shaanxi Province, NW China, which preserves complete forewing venation. Detailed morphological comparison allows us to refine the diagnostic characters of Naibiomorpha and corroborate its phylogenetic placement. This specimen not only provides a key diagnostic benchmark, but lends support to the “forewing miniaturization hypothesis” within the clade. Integrating our findings with palaeobiogeographic data, we infer a Northern Hemisphere origin for Sternorrhyncha in the Permian, followed by a Triassic diversification that gave rise to both extant lineages (e.g., aphids, whiteflies, and psyllids) and extinct groups such as Naibiomorpha.