Análisis comparado de las especies del género Bryconamericus (Teleostei: Characidae) en la cuenca de los ríos Cauca-Magdalena y Ranchería, Colombia

Abstract

We reviewed Bryconamericus species from the Cauca, Magdalena and Rancheria rivers in Colombia using type and new specimens. The geographic distribution of B.caucanus was determined. We determined the morphological variation among Bryconamericus species analyzed using meristic, morphometric and osteological characters. The shape of Bryconamericus was analyzed using principal component analysis (PCA), in which measurements were previously processed to correct for the effect of size. The number of vertebrae differentiated B. caucanus from other species of the Magdalena River (37-39 vs.40-42). Bryconamericus arilepis Roman-Valencia et al 2008 differs from other Rio Magdalena Bryconamericus in lateral-line scales (50-54 vs. 34-50) and scales between dorsal-fin origin and lateral line (9-11 vs. 5-8). The index of form (IF) built with PCA confi rmed the validity of species that share the same shape: B. caucanus Eigenmann 1913 and B. plutarcoi Roman-Valencia 2001, B. tolimae Eigenmann 1913, B. huilae Roman-Valencia 2003, B. arilepis and Bryconamericus sp. nov. Roman-Valencia, Vanegas-Rios and Ruiz-C. in press, and the 2 groups were distinguishable from each other. An ANOVA showed significant differences in pelvic-fin length among species of Bryconamericus (F = 44.7, p = 0000). Anal-fin length was also useful to distinguish the studied species (F = 44.03, p = 0000). Populations of B. caucanus from the lower Rio Cauca show greatest similarity in shape with all other populations from Rio Rancheria, upper and lower Cauca, and middle Magdalena. Hemibrycon dentatus and H. decurrens are shown to be synonyms of B. caucanus . We reconfirm the existence of 2 new species of Bryconamericus from Rio Sogamoso, in the Rio Magdalena basin. The geographical distribution of B. caucanus in the Sinu, Rancheria, Cauca and lower Magdalena river basins is established.