Neoechinorhynchus bullocki n. sp. is described from Catostomus commersonii Lacépède, 1803, from the Otsego Lake watershed, central New York State. Neoechinorhynchus bullocki differs from other catostomid-infecting species in body size and shape, proboscis armature, and characteristics of the male reproductive system. Sequences of the internal transcribed spacer and the large ribosomal subunit (28S) were also used to distinguish this new species. Neoechinorhynchus bullocki is the sixth species of Neoechinorhynchus to be reported from C. commersonii and the seventh species of the genus with a dorsal body wall considerably thicker than the ventral body wall. It is the 34th species of Neoechinorhynchus to be described from fishes of North America. In contrast to many of its congeners, N. bullocki was found to have a strict (i.e., oioxenous) level of host specificity based on an extensive fish parasite survey that took place in New York State over a 10-yr period and included the examination of the intestines of more than 1,800 fish from the fish families Catostomidae, Centrarchidae, Cyprinidae, Esocidae, Ictaluridae, and Percidae.