The monotypic genus Ectrepopterus Fowler was recently resurrected by Malabarba et al. (2012) for Megalamphodus uruguayensis Fowler, a small-sized fish (up to 47.4 mm SL) which habit the Uruguayan drainages (figure 7 of Malabarba et al. 2012). Diagnostic characters for genus include: i) an incomplete foramen in posterior region of metapterygoid, that serves as passage for the ramus mandibularis of the trigeminus nerve, bordered posteriorly by the hyomandibula and forming an incomplete arch; ii) pectoral-fin rays bearing hooks; iii) posterior margin of second infraorbital posteroventrally oblique and second infraorbital ventrally bordering anterior region of third infraorbital; iv) fourth infraorbital more developed longitudinally than dorsoventrally; v) ascending process of premaxilla reaching just anterior end of nasal, vi) and lateral line interrupted (Malabarba et al. 2012).