A new species of the loricariid subfamily Neoplecostominae is described on the basis of specimens obtained from the headwaters of the rio Iguaçu basin in the State of Paraná, southern Brazil. Pareiorhaphis parmula is the first representative of the genus discovered from the rio Paraná basin and expands the geographic distribution of the genus. It is diagnosed from other Pareiorhaphis species by having one small plate on each side of the pectoral girdle, just posterior to the gill opening and the club-shaped pectoral-fin spine, broadening from base to tip in adult males. All species formerly included in Hemipsilichthys except H. gobio, H. papillatus, and H. nimius are transferred to the genus Pareiorhaphis, which is resurrected from the synonymy of Hemipsilichthys.
Neotropical; Systematics; Neoplecostominae; Hemipsilichthys; Isbrueckerichthys
