Nematodes of the family Molineidae are the most frequent helminths reported infecting the digestive tract of South American amphibians. The molineid genus Kentropyxia Baker, 1982 includes only 2 nominal species of parasitic nematodes: Kentropyxia sauria Baker, 1982 and Kentropyxia hylae Feitosa et al., 2015 both from the eastern Amazon. We describe a new nematode species of Kentropyxia parasitizing Boana boans, Boana geographica, and Boana wavrini from 2 different locations in the eastern Amazon. Kentropyxia bakeri n. sp. has corona radiata composed of unequal lappets, a smooth cephalic vesicle, a claviform esophagus, and well-developed cuticular longitudinal ridges composing the synlophe. Females have a well-developed ovojector, with amphidelphic uteri, and a simple tail. Males have a type I copulatory bursa and complex robust spicules divided into an outer process and fan-like branches (1 dorsolateral and 1 ventrolateral) divided into numerous projections. We observed intraspecific variation among specimens from different hosts, which can be related to factors regarding the hosts, the parasite, their location, and/or their ecology. The new species differs from its congeners by the presence of cervical alae composed of a series of modified oblique ridges which are absent in K. sauria but are composed of single expanded cuticle projections in K. hylae. This species is the third described for the genus and the second reported for a hylid host in the Neotropics.