Brachysomophis longipinnis is an eel in the family Ophichthidae (worm/snake eels). It was described by John E. McCosker and John Ernest Randall in 2001. It is a marine, temperate water-dwelling eel which is known from a single specimen collected from Taiwan, China, in the northwestern Pacific Ocean. It is known to dwell at a depth of 50 metres, and is known to reach a total length of 42.1 centimetres.