A new genus, Tupadesmus (Polydesmida, Chelodesmidae), and a new species, T. muyrakyta (type species for the genus) are herein described from the Amazon rainforest of northern Brazil. Tupadesmus pugiunculus (Schubart, 1946), new combination, is placed in the new genus. We compared the new genus with other Chelodesminae taxa, in particular with Eucampesmella, Brachyurodesmus and Arthrosolaenomeridini. Males of the genus Tupadesmus differ from those of other Chelodesmidae genera by the presence of well-defined striations surrounding incisura lateralis and by the gonopodal prefemoral process divided into two thin, elongate, subequal and acuminate branches. An updated checklist of the Chelodesmidae of Pará State, Brazil, is also provided.