A new species, Strymon cryptodes sp.nov. is described from puna grasslands of northern Peru.Its phenotype corresponds with the male paralectotype of a congeneric species originally described as Thecla heodes Druce, 1909, which, in consequence, turns out to be a mixture of two biological species.Males of S. heodes have conspicuous scent patches, absent in S. cryptodes sp.nov.The new species is known from four individuals recently collected in the vicinity of the city of Cajamarca and two historical specimens from other localities in the department of Cajamarca.Based on wing colour patterns and other morphological characters S. cryptodes sp.nov. is placed in the Strymon istapa species-group defined by Robbins & Nicolay (2002), although the presence or absence of male androconial patch and genitalia brush organ are demonstrated not to be a valid diagnostic infrageneric character.