Gomphosus is a genus of tropical fishes that inhabit coral reefs in Indian Ocean and Pacific Ocean. Two species has been described, but only G. varius was recorded in China (Fig. 2). Gomphosus caeruleus Lacepède, 1801, a new record in China, was identified from the specimens collected in a survey of the continental slope of the South China Sea (Fig. 1a). The main morphological characteristics defining this species are: body light tan in female and black in male; snout elongated with upper and lower jaws forming a projecting tube; standard length is 4.2 times of body height and 2.6 times of head length; dorsal fin rays Ⅷ-13, anal fin rays Ⅲ-11, pectoral fin rays i (unbranched) +14 (branched); vertebral bones 25; branchiostegal rays 7; body covered with middle to large size scales; lateral line complete, with 27 pored scales, and the lateral line curved abruptly downward below the posterior portion of soft dorsal fin; 9 small scales attached to the upper operculum, triangular in shape; predorsal scales 8; a black blotch between 1st﹣3rd spines of the dorsal fin; caudal fin truncated in shape. G. caeruleus can be distinguished from sibling G. varius mainly by color. The latter with shading to green in male, yellow to brown anteriorly and dark brown posteriorly in female, and a vertical dark-brown line on each scale of body. Furthermore, G. caeruleus has twice forked canal on lateral line scales, while G. varius has thrice forked canal on scales.