Redescription of Bryconamericus rubropictus (Berg) n. comb. (Ostariophysi, Characidae) and reference to its secondary sexual dimorphism

Resumen

Tetragonopterus rubropictus, briefly described by Berg based on specimens collected in the Molinos River, Salta, Argentina, was transferred to the genus Astyanax Baird & Girard without comments by Eigenmann. Based on the study of type specimens and more extensive material, the species is redescribed. The species possesses the combination of characters that are currently used to define the genus Bryconamericus Eigenmann; thus, the species is transferred to this genus. Principal component analysis on twenty morphometric variables showed that caudal peduncle depth is deeper in adult males than in adult females, and that pelvic, pectoral, anal and dorsal fins are longer in males than in females. Bryconamericus rubropictus seems to be closely related to B. thomasi Fowler. Both species mainly share the enlarged anal fin of males with a strongly convex distal border. Bryconamericus rubropictus differs from B. thomasi by the presence of 14 scales around caudal peduncle (vs. 16), more teeth on smaller posterior dentary series (6-9 vs. 3-6) and some morphometric values. A lectotype is designated for T. rubropictus.