A new geinitziid forewing reveals biostratigraphic correlation between Daohugou and Shar Teg

The Middle–Late Jurassic insect assemblages of the Asian interior, such as the Daohugou and Shar Teg biotas, provide critical windows into insect evolution. These biotas share similar faunal compositions, yet their similarities are largely limited to the generic level. This lack of species-level evidence has hindered precise stratigraphic correlation. In this study, we describe a complete forewing of a geinitziid fossil from the Haifanggou Formation at the Daohugou locality, Ningcheng, Inner Mongolia. The specimen is identified as Sinosepididontus shartegicus Aristov et al., 2009, a species previously known only from a basal wing fragment recovered from the lower Shar Teg sequence in southwestern Mongolia. Based on this well-preserved new material, we provide an emended diagnosis and supplementary description for S. shartegicus, offering the first full characterization of its wing venation. The discovery of S. shartegicus in the Daohugou biota substantially reinforces the biotic link between the Daohugou and Shar Teg assemblages. Based on regional geological data, we correlate the Shar Teg sequence with the Haifanggou Formation, and we further correlate the overlying Ulan Malgait sequence with the Tiaojishan Formation.