Moenkhausia rara sp. n. - a new threatened characid fish (Teleostei: Characiformes: Characidae) from Suriname and French Guyana, with a supplementary description of M. simulata (Eigenmann in Pearson, 1924). Zoologische Abhandlungen (Dresden), 54, 8 November 2004: 19-30. 21 [Zoological Record Volume 141]