Microglanis robustus, new species, is the first Microglanis to be described from the Rio Tocantins basin, Pará, Brazil, and differs from the congeners by the presence of a cordiform blotch in the nape, instead of a transverse light stripe; neuromasts of the superficial lines surrounded by melanophores; robust body with short snout, head and predorsal distance; and deep caudal peduncle. The mapping of superficial neuromasts and cephalic sensory canals evidenced intra and interespecific polymorphisms and, therefore, of little value for phylogenetic analysis within the genus.