Two new species of Knodus (Characidae: Stevardiinae) from the upper rio Tocantins basin, with evidence of ontogenetic meristic changes

ABSTRACT Two new species from the upper rio Tocantins basin are described in Knodus based on traditional definition of genus. The distinguished other congeners by meristic and morphometric characters, such as number cusps premaxillary dentary teeth, scale series between dorsal-fin origin lateral line, orbital diameter body depth. With two species, endemic upstream mouth Paranã, rises to 53 (89 confluence with Araguaia). existence a character that changes through ontogeny (allomery), viz. was detected some regression analysis. Additionally, this paper describes an unambiguous, more informative precise method for counting vertebrae, which will enhance efficacy trait comparisons.