Two new records of worm or spaghetti eel genus <i>Moringua</i> (Anguilliformes: Moringuidae) from estuaries and lagoons in Vietnam

During the survey, eighty-two specimens of the two species were collected from estuaries and lagoons in central Vietnam, including Moringua microchir Bleeker, 1853 and M. raitaborua (Hamilton, 1822), as new records for marine fish fauna of Vietnam with morphometric and meristic details of the species. M. microchir Bleeker, 1853 is characterized by a body depth of 30–44.5 in TL. Head length of 8.7–10.7 in TL, anus far behind a middle length, distances from the tip of snout to the anus are 1.5–1.6 in TL. The pectoral fin is very small and rudimentary, with a length of 10.6–30.5 in HL, and its vertebrae total 105–108. M. raitaborua (Hamilton, 1822) is distinguished by the vertebrae total of 102–104, body depth of 26.7–40.9 in TL, and head length of 7.4–8.7 in TL. Rictus before the posterior margin of the eye, pectoral fin small, but not rudimentary, its length of 3.3–5.8 in HL. We also found some features of them are morphological variations in the ontogenetic stage. They differ significantly in appearance by length group. This discovery may suggest that these two species have extended distribution to Vietnam.