A new species of Carolinensis Travassos, 1937 is proposed for nematodes collected from Sumichrast's vesper rat Nyctomys sumichrasti, an arboreal cricetid of Neotropical rainforests. Carolinensis perezponcedeleoni n. sp. is differentiated from the other 8 species in the genus by the relatively longer spicules and genital cone and by the extension of rays 8, which reach the margins of the bursa. The species shares similarities in the configuration of the bursal rays and conspicuous genital cone with Carolinensis kinsellai, Carolinensis dalrymplei, and Carolinensis tuffi; however, the size of these structures, features of the synlophe, and presence of 2 hook-like projections on the distal end of the genital cone allow the discrimination of the new species.