A new species of scale-worm, Lepidonotopodium atalantae, belonging to the sub-family Lepidonotopodinae (Polychaeta: Polynoidae) has been found in samples collected on the deep-sea hydrothermal vent sites of 9°N and 13°N on the East Pacific Rise. It is mainly characterized by elytra, regularly ornamented on their posterior border, and very long anal cirri. This is the fifth species of Lepidonotopodium, all belonging to the deep-sea hydrothermal vent fauna.