The paper presents the first documentation of Urticaceae-feeding Nepticulidae species in South America and describes four new species: two species feeding on Phenax Wedd. (Stigmella singularia Diškus & Stonis, sp. nov. and S. lata Diškus & Stonis, sp. nov.), one species on Boehmeria Jacq. (S. boehmeriphaga Diškus & Stonis, sp. nov.), and one species on Pilea Lindl. (S. auripurpurata Diškus & Stonis, sp. nov.); all from the equatorial Andes. In addition, leaf-mines of an unknown Stigmella taxa feeding on Phenax are documented. The newly discovered Urticaceae-feeding Nepticulidae exhibit some morphological and taxonomical diversity: two species groups, Stigmella singularia and S. marmorea, are revealed (the latter is designated in the current paper).