Cercophana frauenfeldii Felder, 1862 is a Neotropical saturniid moth endemic to Chile, with a known range extending from central Chile to the Magallanes Region. Based on a male observed at Bahía Tres Brazos, northwest of Gordon Island, this note provides contextual information for a new occurrence record published in the Global Biodiversity Information Facility (GBIF) as occurrence 6235116312, mediated by the iNaturalist Research-grade Observations dataset (https://doi.org/10.15468/ab3s5x). The observation was made in mid‑April 2026 during a small‑boat expedition in the Cape Horn Biosphere Reserve, a sub‑Antarctic archipelago where Lepidoptera have been less documented than many other taxa. The record documents the presence of C. frauenfeldii on a sub‑Antarctic forest island south of the mainland Magellanic sector, in line with previous reports from the Magallanes Region (including Puerto Williams, Omora Park) and with the distribution of its host tree Drimys winteri. By combining opportunistic naturalist observations with open infrastructures such as GBIF, this contribution complements existing Chilean work on the species by refining its known southern distribution and illustrating how low‑intensity fieldwork from small vessels can support future biogeographical and conservation studies in southern South America.