|In this study, the genus Isorineloricaria Isbrücker 1980 is resurrected and redescribed. The complex history of the genus is reviewed. Isorineloricaria is diagnosed from Hypostomus by an elongated caudle peduncle, elongate hypertrophied breeding odontodes on nuptial males, central buccal papilla enlarged or multiple buccal papillae and from most Hypostomus by their lighter background coloration. The species of Isorineloricaria are redescribed and diagnosed; Plecostomus annae and Hypostoma squalinum are placed in the synonymy of I. emarginata; Plecostomus biseriatus, P. scopularis, and P. virescens are placed in the synonymy of I. horrida; Plecostomus winzi is placed in the synonymy of I. tenuicauda, and one new species is described from the Apure River basin of Venezuela. Speceis are largely allopatric and separated by color pattern. Species recognized as taxonomically valid are: I. ammophila from the Apure and Orinoco Rivers in Venezuela; I. emarginata from the lower Amazon River and it’s tributaries; I. gomesi from Jaguaribe River, Ceará state, Brazil; I. horrida from the upper Amazon River, including the mainstem, Rio Napo, Rio Marañon, Rio Ucayali, Rio Juruá, Rio Purus, and Rio Madiera; I. phrixosoma from the Rio Ucayali, Peru; I. spinosissima from the Guayas River basin, Ecuador; I. tenuicauda from the Magdalena River basin in Colombia; I. unicolor from from upper Amazon tributaries of Bolivia, Brazil, Colombia, Ecuador, and Peru; I. villarsi from the Maracaibo basin in northwestern Venezuela and extreme eastern Colombia; Isorineloricaria n. sp. ‘Apure’ is described from the Apure and Orinoco Rivers in Venezuela. Photos of specimens and range maps are updated, and biogeorgaphic patterns and their relationships with hypothesized geologic events across the South American continent are also discussed. During the middle to late Miocene, the vicariant events that divided the Magdalena and Maracaibo basins from the Amazonas and Orinoco rivers were very important in the evolution of Isorineloricaria, allowing for the rise of several of the taxa seen in the region. Furthermore, the rise of the Andes may have allowed the invasion of the piedmont areas by the smaller members of Isorineloricaria, such as I. ammophila, I. phrixosoma, and I. unicolor.