The spiny eel genus Sinobdella belongs to the family Mastacembelidae of the order Synbranchiformes. Kottelat and Lim (1994) utilised Rhynchobdella sinensis as the type species to propose the genus. Currently, it contains a single species widespread in eastern and southern China and northern Vietnam. Sinobdella longitubulus, a new species of spiny eel, is here described from the Xi-Jiang of the Zhu-Jiang Basin in Guangxi Zhuang Autonomous Region, southern China. It differs from the single congeneric species S. sinensis in having a more or less white-brown reticulated pattern on the flank, two tubular anterior nostrils longer than or equal to the rostral appendage, an anal fin heavily mottled with dark brown markings and white spots and bearing a narrow white distal margin; shorter pre-anal length; and fewer abdominal vertebrae. The validity of this new species is corroborated by its monophyly recovered in a COI gene-based phylogenetic analysis and its significant sequence divergence with S. sinensis. A note on the type locality of S. sinensis is also given; its type specimen is possibly from mountain streams of Jiangxi Province, in the lower Chang-Jiang Basin.