Gnathostoma spinigerum has a deep reddish body. Females are larger. The body features eight to eleven series of minute hooklets. The cephalic region bears leaf-like spines, while the posterior portion is curved ventrally and smooth. The mouth is surrounded by two fleshy lips and opens into a muscular oesophagus. Males have four pairs of pedunculate papillae and two unequal chitinous spicules.