Holotype: 1 ♂, PERU, Dept. Lima, 10 km N of Oyon, Quabrada Quichas, Pueblo Quichas, 10°34'17"S, 76°46'03"W, elevation ca. 4000 m, 24–26.ii.1987, O. Karsholt, genitalia slide no. Diškus 188♂ (ZMUC).
type genitalia preparation:
Zoological Museum, Natural History Museum of Denmark, Copenhagen (ZMUC)
The species is named after other, closely similar species—Stigmella epicosma (Meyrick) but with a different Latin prefix alti (high) in reference to the occurrence of S. alticosma sp. nov. in high altitudes.