A new archostematan beetle, Rotunthorax jiyuanensis gen. et sp. nov., is described based on a well-preserved specimen from the Middle-Late Triassic of Jiyuan (Henan Province, North China). Rotunthorax gen. nov. is distinguished from other closely related genera by its rounded and undecorated pronotum, the absence of a distinct neck between the head and pronotum, and more gently sloping sides. The new species is characterized by a slender body exhibiting six visible rows of window punctures, robust and inwardly curved mandibles, slightly separated procoxae, longitudinally oval window punctures, and broad epipleura.