Two new snake eels (Anguilliformes, Ophichthidae, Ophichthus) from Viet Nam, with redescriptions of O. macrochir (Bleeker) and O. rutidoderma (Bleeker)

Two new extremely elongate snake eel of the genus <i>Ophichthus</i> are described based on specimens collected from Vietnamese waters. <i>Ophichthuscuulongensis</i> Vo, Hibino & Ho, <b>sp. nov.</b> is distinguished from its congeners by having the dorsal-fin origin slightly behind the pectoral-fin tip, mean vertebral formula 14-63-202, range 12-17/60-64/199-207; teeth on jaws biserial to triserial; dorsal body dark brown, ventral body pale, anal fin initially white but changing to darker towards its tip. <i>Ophichthusnguyenorum</i> Vo, Hibino & Ho, <b>sp. nov.</b> is distinguished by having a snout rather pointed but the occipital convex (duck-shaped); body with numerous longitudinal wrinkles, weak on posterior abdomen; dorsal-fin origin slightly behind the pectoral-fin tip; one row of teeth on the maxilla anteriorly but increasing posteriorly; two rows on the lower jaw; all teeth small; body dark, usually including abdomen; dorsal fin darker with dark margin; anal fin initially pale but changing to darker towards tip; mean vertebral formula: 15-62-192, range 13-17/61-64/190-196. Descriptions of two related species, <i>O.macrochir</i> (Bleeker, 1852) and <i>O.rutidoderma</i> (Bleeker, 1852), are provided with updated morphological data.