Syringolaimus is the most abundant and diverse genus ofthe family Ironidae (Nematoda) found in the Campos Basin, off
Rio de Janeiro, BraziL In this article, four new species ofthis genus are described, S annae sp. n. is characterized by a conical-cylindrical tail without a spinneret S magdae sp. n, possesses a pair of ejaculatory glands located in the precloacal region, and a spinneret, which comprises 212% of the total tail length,. In S. smolae sp. n. the spicule is setiform. S. taniae sp. n. has the anterior region ofthe tail rounded, with its terminal portion cylindrical-filiform.