Two new species of the suckermouth armored catfish genus Baryancistrus are described from the Jari River basin, at the border of Pará and Amapá states, Brazil. The new species are the first representatives of the genus described from rivers draining the Guiana shield, and can be distinguished from their congeners by color pattern and a combination of nonexclusive characters. Baryancistrus micropunctatus, new species, has a color pattern similar to B. longipinnis from the Tocantins River, whereas Baryancistrus hadrostomus, new species, has a color pattern that is unique for the genus, with a gray to black body covered by small and widely spaced white points. The first exemplars of the two new species were collected in the late 1980s by INPA ichthyological staff, and in 2007 additional materials were collected by the Museu de Zoologia da Universidade de São Paulo (MZUSP), providing a foundation for this description of the new species.