A new genus and species Sinosymphytopterus ningchengensis n. gen. n. sp. and a new species Symphytopterus rasnitsyni n. sp. of the subfamily Symphytopterinae in Ephialtitidae are described and illustrated from the Middle Jurassic Daohugou beds of Ningcheng, Inner Mongolia, Northeast China. The keys to both the genus Symphytopterus and the subfamily Symphytopterinae are updated. These findings increase the diversity of Symphytopterinae, especially in the Daohugou Biota. So far, six ephialtitid genera are common between the Middle Jurassic Daohugou Biota, China and the Late Jurassic Karatau Biota, Kazakhstan, confirming a close relationship between these two biotas. Among these six genera, five show a lower species diversity in the Daohugou Biota than in the Karatau Biota. And such a trend in diversity at both the genus and species levels is also shown in both Ephialtitidae and Symphytopterinae among these two biotas. New discoveries also confirm that the Daohugou Biota is older than the Karatau Biota. (c) 2026 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS