Bothriolepis sinensis Chi 1940, mainly based on anterior median dorsal plates from the Middle Devonian Tiaomachien Formation of Hunan, is the first Paleozoic vertebrate taxon erected in China. Although additional materials of B. sinensis from the type locality were described by Lu in 1988, its morphology and phylogeny remain poorly understood. In this study, we complemented the morphology of the skull and trunk armor of B. sinensis based on Chi’s specimens housed in the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, and several previously undescribed specimens in the Geological Museum of China. Bothriolepis sinensis differs from other Bothriolepis in the following combination of characteristics: enlarged supraotic thickening, length/width ratio of head shield 1.4-1.6, broad orbital fenestra (greater than 1/3 of the head shield width), and fan-shaped preorbital recess. The phylogenetic analysis did not place B. askinae in the most basal position of the genus and revealed that B. sinensis and B. kwangtungensis consistently from a monophyletic group characterized by their slender proximal segment of the pectoral fin (length/width ratio greater than 7). A majority of Chinese Bothriolepis species (B. niushoushanensis , B. lochangensis , B. tungseni , B. kwangtungensis and B. sinensis ) were clustered in a clade characterized by the pectoral pit-line on the ventral central plate 1 extending to the ventral central plate 2. The paleogeographic reconstruction using the data from the DeepBone platform showed that Bothriolepis had its oldest occurrences in South China and East Gondwana in Eifelian, dispersed rapidly worldwide, and then diversified across the coasts of the Rheic Ocean.
