A new species of AlippistrongylusDigiani and Kinsella, 2014, was found in the intestines of the elegant rice rat, Euryoryzomys nitidus, collected in the Amazon rainforest. These mammals were preserved in alcohol and archived in the Colección Científica de Mamíferos del Museo de Historia Natural de la Universidad Mayor de San Marcos and accessed for the observation and investigation for the diversity of their endo-parasites. A total of 857 worms were recovered from the 3 individuals examined. Morphological investigations and comparisons with the only known species of the genus indicate that this is an undescribed species. These nematodes feature the diagnostic characteristic of the genus, being a bifurcated posterior end that consists of a tail and a conical appendage near the level of the vulva and uninterrupted ridges in the synlophe of unequal size. However, the orientation of this conical appendage on the female tail, features of the synlophe, and shape of the copulatory bursa warrant the proposal of an amended diagnosis to include character variability detected in the new species.