Review of the armoured catfish genus Hypostomus (Siluriformes: Loricariidae) from the Parnaiba River basin. Northeastern Brazil, with description of a new species

The species of Hypostomus from the Parnaiba River basin were reviewed through molecular and morphological analysis. Five species were found in the basin, including a new species herein described. The distribution of H. pusarum was expanded to this basin, and a closely related species was recorded (H. aff. pusarum), also the presence of H. johnii and H. vaillanti was confirmed. The new species is distinguished from most congeners by its large number of premaxillary and dentary teeth, a wide dental angle of 115 degrees to 135 degrees, presence of a rounded dark spots on a lighter background and anteromedial region of the abdomen depleted of plaques (vs. anteromedial region of the abdomen covered by platelets and odontodes in H johnii, H. pusarum, H. aff. pusarum and H. vaillanti). Furthermore, an identification key of the species from the Maranhao-Piaui ecoregion and maps with the geographic distribution of these species are presented. The species of Hypostomus in the Parnaiba River basin have different geographic distributions, suggesting different niches or geographical barriers, providing an opportunity for ecological and evolutionary studies.