A new snake eel, Ophichthus longicorpus, is described from 13 specimens from Lương Sơn, Nha Trang, Vietnam. It is distinguished by having dorsal-fin origin situated at 4.4‒6.7 pectoral-fin length behind head;anus situated at about middle of total length; trunk very long, 4.1‒4.9 head length; head length 10.5‒12.2 in TL;posterior nostril above upper lip, covered by a large flap extending well below the edge of mouth gape; pectoral finsmall, pointed posteriorly; no barbel on upper lip; cephalic sensory pores: SO 1 + 4, POM 6 + 2; teeth moderatelylarge and conical, biserial anteriorly and uniserial posteriorly on both jaws and vomer; body colour yellowishbrown dorsally and grayish-brown ventrally; dorsal fin light grayish with indistinct white margin; anal fin whitewith slightly grayish base; and total vertebrae 156–164, mean vertebral formula 27-68-159. Specimens of Echelus polyspondylus McCosker & Ho are newly reported from Vietnam.

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