Two new for science species of the family Oncholaimidae Dujardin, 1845, found in coral reefs in Vietnam, are described and illustrated. Oncholaimus securus sp. n. is close to O. longispiculosus Gerlach, 1955 according to presence of papilla on tail and spicules length. It differs from it by the longer and thinner body, shorter pharynx and wider labial region. Viscosia graciloides sp. n. in body size and length of spicules is close to V. erasmi Furstenberg, Vincx, 1989, V. macrobursata Keppner, 1987 and V. dossena Leduc, Zhan, 2023. It differs from these species by the form of outer labial sensillae, thinner body, narrower labial region and shorter stoma.
Vietnam, coral reefs, free-living nematodes, new species
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