Abstract: A new basal dipnomorph sarcopterygian, Arquatichthys porosus gen. et sp. nov., from the Lower Devonian (Pragian) of northeastern Yunnan, China, is described on the basis of a nearly complete mandible and several isolated scales. It closely resembles basal dipnomorphs in following characters: short and L-shaped pit-line of infradentary 4 (uniquely shared with dipnomorphs), small parasymphysial dental plate attachment, three coronoids, broad “tooth pavement” on the lateral portion of coronoids, large adductor fossa, irregularly scattered pores of mandibular sensory canal on the lateral surface of mandible, and distinct anteroventral process of rhomboid scale. Arquatichthys has a unique mandible morphology characterized by a strongly arched upper margin, and an elongated overlapped area by quadratojugal and maxillary. As the second dipnomorph from the Pragian of China, Arquatichthys adds evidences to understanding the early diversification of sarcopterygians. The character transitions of scales are discussed within the framework of the interrelationships of early sarcopterygians.