This report describes a new species of aspidoderid nematode, Ansiruptodera scapteromi sp. nov., the second species to be reported in the genus Ansiruptodera Skrjabin and Shikhobalova, 1947. The A. scapteromi sp. nov. is the first species of the genus to be recorded from a rodent host. The new species is clearly different from the only other species, A. ansiruipta (Proença, 1937) Skrjabin and Shikhobalova, 1947, in that it possesses short lateral alae that terminate before the midbody; a smaller cephalic extremity; a shorter esophagus, pharynx, tail, and tail appendage; a smaller sucker; and longer spicules. The two species also differ in the numbers and arrangements of caudal papillae. A. scapteromi appears to be a parasite of capture and the water rats seem to have been infected from Edentata in Uruguay.