A new species of Leporinus Agasssiz, 1829 from the upper Rio Paraná basin (Characiformes, Anostomidae) with redescription of L. Elongatus Valenciennes, 1850 and L. Obtusidens (Valenciennes, 1837) - Britski, Heraldo A; Birindelli, Jose Luis Olivan; Garavello, Julio Cesar (Papéis Avulsos de Zoologia, 2012)