A new species of Microschemobrycon with a restricted distribution was recently discovered in the Rio Curuá, Rio Xingu basin, Pará, Brazil. Microschemobrycon cryptogrammus new species can be promptly distinguished from all congeners by the presence of a rounded, dark, conspicuous caudal-peduncle blotch and by a subjacent dark midlateral stripe visible in life. Additionally, the new species can be distinguished from all its congeners, except M. elongatus, by the presence of a longitudinal dark stripe along the lower jaw. The new species can be distinguished from M. elongatus by presenting lateral line with 36-38 pored scales, anterior and posterior nostrils coalescend, dark chromatophores concentrated along the ventral margin of the caudal peduncle and by the presence in life of a dark spot at the base of the dorsal-fin origin.